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YAML Trainer

Private corporate batches, live online cohorts and 1-on-1 mentoring in configuration correctness — the data format that declares almost every modern system — taught by a practitioner who runs it in production.

20 years across DevOps, SRE and Security · 10,000+ engineers trained · Trained teams at JPMorgan Chase, Verizon, Nokia and the World Bank

DeliveryOnline · Onsite · Hybrid
FormatsCorporate · 1-on-1 · Cohort
AgendaCustomisable
Batch size8–30 engineers
Engineers we've trained work at
JPMorgan ChaseBank of AmericaWells FargoVerizonNokiaWorld BankGE HealthcareVMwareOracleQualcommMercedes-BenzAirbusDatadogSplunkDeloitteInfosysWiproCapgemini
# who teaches it

Your YAML trainer

Rajesh Kumar

Principal DevOps Engineer & Architect

Early-bird MLOpsAIOps practitionerData platform operations20 years in productionPrincipal / architect roles10,000+ engineers trainedM.Tech BITS Pilani25+ certifications

Rajesh teaches YAML as a correctness problem rather than a syntax lesson — the implicit typing rules behind the unquoted-boolean and leading-zero failures, block versus flow style, literal and folded scalars with their chomping indicators, and anchors, aliases and merge keys with the tooling divergence that makes them risky. Sessions cover the validation layer most teams are missing: JSON Schema over YAML, yamllint and kubeconform in CI, policy checks with conftest, and testing the rendered output of Helm and Jinja2 templates rather than the templates themselves.

Twenty years across DevOps, SRE and Security, in principal and architect roles at PayPay, SoftwareAG, ServiceNow, JDA Software, Intuit, Adobe and others. He has trained engineers at JPMorgan Chase, Verizon, Nokia, the World Bank, VMware, Oracle, Mercedes-Benz and Airbus — more than 10,000 people personally. He teaches what he runs, not what he reads.

One practitioner, not a bench

You are booked with a named engineer, and that is who turns up. Marketplaces and larger providers rotate whoever is free, so the person who sold you the agenda is rarely the person teaching it.

The same trainer is available for the next engagement, which matters when a team builds on what it learned last time.

18,000+certified learners
500+corporate batches delivered
50+countries served
100+certification programmes
# faculty

Who delivers YAML engagements

Your batch is assigned a named trainer before it starts, and that is who teaches it. See the full faculty.

How your YAML trainer is chosen

Engagements are matched on the tool, not the calendar. For YAML that means a trainer who has run it in production — configuration correctness — the data format that declares almost every modern system — rather than whoever is free that week. You are told who is teaching before you commit, and that person is on the discovery call that shapes the agenda.

Where a batch is large enough to need a second trainer, the pairing is declared up front. The lead trainer stays accountable for the syllabus and the assessment either way.

Rajesh Kumar

Principal DevOps Engineer & Architect

India20 yrsLead trainer

Twenty years across DevOps, SRE and Security in principal and architect roles at PayPay, SoftwareAG, ServiceNow, JDA Software, Intuit, Adobe, IBM/Emptoris, Ness, MindTree and Accenture. He has trained more than 10,000 engineers personally, at organisations including JPMorgan Chase, Verizon, Nokia, the World Bank, VMware, Oracle, Mercedes-Benz and Airbus. He teaches what he runs, not what he reads.

Durga Prasad

IndiaInstructorCoach

Gaurav Aggarwal

IndiaInstructorCoach

Harsh Mehta

IndiaInstructorCoach

Kapil Gupta

IndiaInstructorCoach

Kunal Jain

IndiaInstructorCoach

Nikhil Gupta

IndiaInstructorCoach

Pranab Kumar

IndiaInstructorCoach

Rohit Ghatol

IndiaInstructorCoach

Amit Agarwal

IndiaInstructorCoach

Anil Kumar

IndiaInstructorCoach

Balachandran Anbalagan

IndiaInstructorCoach

# how to engage

Four ways to work with this trainer

Private corporate batch

Teams of 8–30

Custom agenda, your timezone, onsite or online, NDA-friendly.

Request a quote

1-on-1 mentoring

Individual engineers

A private instructor and a curriculum built around your goal.

₹99,999

Live & Interactive cohort

Individuals who want peers

Scheduled batch, max 8 to 10 hours of live instruction.

₹34,999

Self-paced video

Self-starters

Full LMS access — 20+ courses and 50+ tools included.

₹833/mo
# private batches

Private YAML training for your team

A private batch starts with a discovery call. We look at the stack you actually run — the CI system, the cloud, the constraints — and map the agenda onto it, so examples use your topology rather than a generic one.

Delivery is onsite at your premises, live online, or hybrid, scheduled around your release calendar rather than ours. Batches run 8 to 30 engineers.

Every attendee leaves with recordings, slides, lab repositories and a completion certificate. You receive an attendance and assessment report. Invoicing supports PO and GST.

Talk to us about a private YAML batch

What you provide vs what we bring

  • You: the room or the call, and the engineers
  • Us: trainer, agenda, labs, assessment, certificates
  • Labs: we guide your team through provisioning their own free-tier cloud environment — the skill goes with them
# the technology

What is YAML?

YAML is a data serialization format, not a tool and not a language. It defines a small data model — scalars, sequences and mappings, arranged into documents and streams — and a human-oriented syntax for writing it down. Every JSON document is valid YAML 1.2, so YAML is best understood as JSON with indentation instead of braces, plus a set of conveniences: comments, multi-line strings, anchors for reuse, multiple documents in one file, and implicit typing that infers whether a bare token is a string, a number, a boolean, a timestamp or null.

That convenience is also the risk. Because YAML infers types, the unquoted value no becomes false, 08 is rejected as an invalid octal number under some parsers, 1.10 becomes the number 1.1, and a version string loses its trailing zero. Because it is indentation-sensitive, a single misplaced space silently changes a key's parent rather than raising an error. Because anchors and merge keys are resolved at parse time, a template that emits them can produce a document that is valid YAML and completely wrong. None of these produce syntax errors — they produce a well-formed document that means something other than what the author intended.

That matters because YAML is now the declarative surface of the entire infrastructure stack: Kubernetes manifests, CI pipeline definitions, configuration management playbooks, container compose files, OpenAPI specifications, cloud templates, policy bundles and application configuration. Treating it as a format worth understanding precisely — with schemas, linting and validation in CI — is the difference between catching a defect on a pull request and discovering it during a deployment.

Why this skill matters now

Infrastructure moved into the repository, and the repository is full of YAML. A platform team of ten now maintains thousands of manifests, pipeline definitions, values files and policy documents, and every one of them is executable configuration with production consequences.

The tooling around that has not kept pace with the volume. Most organisations still merge YAML with no schema validation, no linting beyond whitespace, no test for the rendered output of a template, and no policy gate — so the first thing that checks the document is the cluster or the pipeline that applies it. The resulting incident class is recognisable everywhere: a boolean that was meant to be a string, a value indented under the wrong key so a limit was never applied, an anchor overridden in a way the author did not expect, a Helm template that emitted valid YAML with the wrong nesting, a secret committed in plaintext because YAML made it easy.

The skill in demand is not YAML syntax, which takes an afternoon. It is configuration correctness: knowing the failure modes, writing or adopting schemas, validating rendered output rather than templates, and putting the whole thing behind a CI gate so bad configuration cannot merge.

YAML training
# outcomes

What your team can do afterwards

Read any YAML document precisely — nodes, documents, streams, block and flow style — and predict exactly what a parser will produce
Avoid the implicit-typing failures that reach production: unquoted booleans, leading zeros, version strings, timestamps and nulls
Use literal and folded multi-line scalars correctly, including indentation and chomping indicators for scripts and certificates
Apply anchors, aliases and merge keys for reuse, and recognise where tooling divergence makes them unsafe
Write and apply JSON Schema to YAML so invalid configuration fails on a pull request rather than at deploy time
Gate configuration in CI with yamllint, schema validation, kubeconform and policy checks such as conftest
Diagnose templating failures in Helm and Jinja2 by validating rendered output, indentation and injected quoting
Keep secrets out of plaintext YAML using SOPS, sealed secrets or an external secret store, and enforce it with a scanner
# curriculum

7 modules. Live demos in a real lab, not slides.

01The YAML data modelLive & Interactive5 hrs · 2 assignments · 1 capstone

What YAML actually defines, separated from the tools that consume it. Nodes, scalars, sequences and mappings; documents, directives and streams; the relationship to JSON; block versus flow style; comments; and the version differences between YAML 1.1 and 1.2 that still cause real divergence between parsers.

Topics: Scalars, sequences and mappings — the whole data model · Documents, the --- separator, ... terminator and multi-document streams · YAML as a superset of JSON, and what that means in practice · Block style versus flow style, and when each is appropriate · Comments and why they do not survive most round-trips · YAML 1.1 versus 1.2 and parser divergence · Which parser your tool actually uses, and why it matters

  • Assignments: (1) Convert a nested JSON document to YAML by hand and verify equivalence with a parser; (2) Load the same document with two different parsers and identify every difference
  • Capstone: Produce a reference note on the exact YAML dialect your tooling accepts
02Scalars, implicit typing and quotingLive & Interactive5 hrs · 2 assignments · 1 capstone

The module that prevents the most incidents. How YAML decides whether a bare token is a string, integer, float, boolean, timestamp or null; the well-known failure cases; the differences between plain, single-quoted and double-quoted scalars; escape sequences; and explicit tags when inference must be overridden.

Topics: Implicit typing and the core schema resolution rules · Booleans: the unquoted no, y, on and off problem · Numbers: leading zeros, octal interpretation, underscores and version strings · Null, empty and the four ways to write nothing · Timestamps and dates inferred where a string was meant · Plain, single-quoted and double-quoted scalars and their escape rules · Explicit tags — !!str, !!int — and forcing a type · Unicode, special characters and reserved indicators

  • Assignments: (1) Predict the parsed type of thirty scalar values, then verify every one against a parser; (2) Find and fix the type-inference defects in a supplied configuration file
  • Capstone: Write a quoting standard for your repositories with a rationale for each rule
03Structure, indentation and multi-line scalarsLive & Interactive5 hrs · 2 assignments · 1 capstone

The layout rules and the block scalar forms that carry scripts, certificates and embedded configuration. Indentation as structure, nesting sequences inside mappings, the literal and folded styles, chomping and indentation indicators, and the whitespace mistakes that change meaning without producing an error.

Topics: Indentation as structure, and why tabs are forbidden · Nesting sequences within mappings and the optional-indent ambiguity · Complex keys and the ? indicator · Literal block scalars with | for scripts and keys · Folded block scalars with > and how line folding actually works · Chomping indicators: strip, clip and keep · Explicit indentation indicators for content starting with spaces · Long lines, wrapping and readability in review

  • Assignments: (1) Embed a shell script and a PEM certificate in YAML so both survive a parse-and-emit round trip; (2) Diagnose three documents where a value silently attached to the wrong parent key
  • Capstone: Build a configuration file with embedded scripts and verify the rendered output byte for byte
04Anchors, aliases, merge keys and reuseLive & Interactive5 hrs · 2 assignments · 1 capstone

YAML's built-in reuse mechanism, its practical uses in pipeline and compose files, and its limits. Anchors and aliases, the merge key and its override semantics, nesting and ordering rules, tool-specific extensions — and the reasons many teams deliberately forbid all of it.

Topics: Anchors and aliases: definition, reference and scope · The merge key and override precedence · Multiple merges and ordering · Reuse patterns in CI pipeline definitions · Where anchors break: cross-document, cross-file and templated output · Merge keys in YAML 1.2 and inconsistent parser support · Denial of service through alias expansion · Alternatives: templating, overlays and composition tools

  • Assignments: (1) Refactor a repetitive pipeline definition using anchors and merge keys; (2) Demonstrate a case where an alias produces the wrong result after templating
  • Capstone: Produce a team policy on anchors — where they are allowed, where they are banned, and why
05Schemas and validationLive & Interactive5 hrs · 2 assignments · 1 capstone

Turning YAML from free text into something verifiable. JSON Schema applied to YAML documents, writing a schema for an internal configuration format, editor integration so mistakes surface while typing, and the ecosystem validators — yamllint, kubeconform, OpenAPI, CUE — with an honest comparison of what each catches.

Topics: Why syntax validity is not correctness · JSON Schema over YAML: types, required properties, enums and patterns · Writing a schema for an internal configuration format · Composition: allOf, oneOf, conditionals and defaults · Editor and language-server integration for live validation · yamllint for style and structural rules · Kubernetes manifest validation with kubeconform · OpenAPI as a schema-first YAML contract · CUE and typed configuration in outline · Choosing what to validate and what to leave open

  • Assignments: (1) Write a JSON Schema for one of your real configuration files and validate the whole repository against it; (2) Configure editor validation so a schema violation is visible before commit
  • Capstone: Deliver a published schema for an internal format, with editor integration and documentation
06Templating YAML and why it goes wrongLive & Interactive5 hrs · 2 assignments · 1 capstone

The single largest source of YAML defects in modern estates: generating an indentation-sensitive format with a text templating engine that does not understand it. Go templates and Helm, Jinja2, the indentation and quoting failure modes, and the structural alternatives that avoid the problem entirely.

Topics: Text templating an indentation-sensitive format — the core problem · Go templates and Helm: values, defaults and conditionals · indent and nindent, and the errors they exist to solve · Quoting injected values: the toYaml and quote functions · Jinja2 templating in configuration management contexts · Whitespace control and the blank-line and trailing-space traps · Validating rendered output rather than the template · Structural alternatives: Kustomize overlays, jsonnet, CUE · Snapshot testing rendered manifests in CI

  • Assignments: (1) Debug a chart that renders valid YAML with the wrong nesting and fix the indentation handling; (2) Add rendered-output snapshot tests to a template so a regression fails the build
  • Capstone: Build a template with rendered-output validation and snapshot tests wired into CI
07YAML in production — security, secrets and estate hygieneLive & Interactive5 hrs · 2 assignments · 1 capstone

Operating a large YAML estate safely. Keeping secrets out of plaintext, the deserialization vulnerabilities that come from unsafe loading, the review and merge-conflict problems that come from thousands of near-identical files, and building the CI gate that ties every earlier module together.

Topics: Secrets in YAML: why base64 is not encryption · SOPS, sealed secrets and external secret stores · Secret scanning as a pre-commit and CI gate · Unsafe deserialization: arbitrary object construction and safe loading · Alias expansion limits and parser hardening · Merge conflicts, ordering and diff noise in large YAML files · Formatting, key ordering and canonicalisation for reviewable diffs · Policy as code with conftest and OPA · Assembling the full gate: lint, schema, policy, render, test · Documenting configuration so it survives its author

  • Assignments: (1) Remove a plaintext secret from a repository and replace it with an encrypted or referenced value; (2) Demonstrate an unsafe-load vulnerability and close it
  • Capstone: Deliver a complete configuration quality gate that blocks a bad merge on a real repository

Need this mapped to your stack?

We rebuild the agenda around the tools you actually run.

Request a custom agenda
# hands-on

Labs and capstones your engineers actually build

LAB · TYPES

Thirty scalars, thirty predictions

Predict the parsed type of thirty ambiguous scalar values — booleans, leading zeros, version strings, timestamps, nulls — then verify each against two parsers and explain every disagreement.

implicit typingquotingparsers
LAB · STRUCTURE

The value under the wrong key

Work through configuration files where indentation silently reparented a value, find each one without a syntax error to help you, and build a lint rule that catches the class.

indentationyamllintstructure
LAB · SCHEMA

Fail it on the pull request

Write a JSON Schema for a real internal configuration format, wire it into the editor and into CI, and prove that three previously-shipped defects now fail before merge.

json schemavalidationci
LAB · TEMPLATES

Valid YAML, wrong document

Debug a Helm chart that renders syntactically valid YAML with incorrect nesting and unquoted injected values, then add rendered-output snapshot tests so it cannot regress.

helmnindentsnapshot tests
LAB · SECRETS

Get the secrets out

Find plaintext credentials across a repository's YAML, migrate them to encrypted or externally referenced values, and add a scanner that blocks the next one.

sopssecretsscanning
CAPSTONE · GATE

A configuration quality gate

Assemble lint, schema validation, manifest validation, policy checks and rendered-output tests into one CI gate, and demonstrate it blocking five distinct classes of bad configuration.

conftestkubeconformpipeline
# ecosystem

The tools YAML sits next to

Kubernetes
Helm
Ansible
GitHub Actions
GitLab CI
Docker Compose
OpenAPI
JSON Schema
yamllint
kubeconform
SOPS
Open Policy Agent

Who this is for

  • Platform and DevOps engineers maintaining large manifest and pipeline estates
  • SREs investigating incidents that trace back to a configuration value
  • Kubernetes engineers writing manifests, charts and Kustomize overlays
  • Configuration management engineers writing playbooks, roles and inventories
  • Developers who edit CI definitions and application configuration without owning the format
  • Security and compliance engineers enforcing policy over configuration as code

Pre-requisites

  • Comfortable on a command line and with a text editor or IDE
  • Familiarity with Git and pull-request review workflow
  • Working exposure to at least one YAML-driven tool — Kubernetes, a CI system or configuration management
  • Basic understanding of JSON and structured data
  • A repository with real YAML you are allowed to lint, validate and refactor
# pricing

Straightforward pricing

Every plan includes 1 year of full LMS access — not just this course, the entire DevOpsSchool LMS: 20+ courses, 50+ tools, videos, quizzes, assignments and projects.

Self-paced video

₹833/mo

Billed yearly at ₹9,996

Enroll now

1-on-1 mentorship

₹99,999

Full program, private instructor

Enroll 1-on-1

Corporate / private batch

8–30 engineers · custom agenda · onsite or online · PO and GST invoicing

Get a custom quote

Refunds. If we cancel or postpone a cohort, you get a full refund within 15 days. There is no money-back guarantee otherwise.

Terms. Course material remains licensed to the attendee. Read the terms.

Your data. We don't share it with third parties. Privacy policy.

Every attendee gets a verifiable certificate

  • Issued per attendee on completion
  • Verifiable at devopsschool.com/certificates
  • Hard copy available on request
  • Corporate batches receive an attendance and assessment report
DevOpsSchool

YAML Training

Certificate of completion

# feedback

What engineers say

4.4 / 5 from 26 reviews on Trustpilot.

★★★★★
Rajesh is a very good trainer I have experienced in DevSecOps training. The number of contents in different topics he has posted on the DevOpsSchool public website are amazing and user friendly for beginners and experienced professionals.
Ashutosh Mishra · Trustpilot
★★★★★
The trainer (Rajesh) provided very good sessions on SRE profession. Not only hands-on learning on the tools but also SRE mindset.
Peter Wang · Trustpilot
★★★★★
Very good training session. Well explained from the basics to the complex concepts. Also tried to cover practicals and demos within the 3 hour sessions. The learning content and videos are of a great deal of help.
Sreekanth Kannoth · Trustpilot
★★★★★
Basics explanation was exemplary from Rajesh where he dealt with complicated topics to be simple. Great learning stuff personally for me.
Krishna Mohan Yelleti · Trustpilot
★★★★★
Very detailed explanation and has lots of patience in attending the questionnaire. Thanks again for your wonderful sessions.
Uttam Samudrala · Trustpilot
★★★★★
Good discussion, helped us to understand different tools in SRE.
Prashant Saxena · Trustpilot
# comparison

Why a named practitioner beats a marketplace listing

What mattersYouTube + blogsGeneric online courseFreelance marketplaceDevOpsSchool
Named practitionerNoRarelyVaries per bookingYes — same trainer each time
Production experienceUnknownUnknownUnverified20 years, named employers
Custom agendaNoNoSometimesBuilt from your stack
Onsite deliveryNoNoSometimesYes
Lab environmentNoneSandbox that expiresVariesYour own cloud — skill goes with you
AssessmentNoneQuizRarelyAssignments + capstone per module
Per-attendee certificatesNoSometimesRarelyYes
Corporate invoicingNoLimitedVariesPO and GST
Post-training supportNoneForum, time-limitedNoneLifetime forum access
# questions

Frequently asked

Can the agenda be customised for our stack?
Yes — that is the normal case for a private batch. We start with a discovery call, look at the CI system, orchestrator and templating tools you actually run, and rebuild the module list around them. Examples then use your repositories rather than a generic one.
Do you deliver onsite?
Yes. Private batches run onsite at your premises, live online, or hybrid. You provide the room and the engineers; we bring the trainer, agenda, labs, assessment and certificates.
What lab environment do we need?
Attendees provision their own environment — free-tier AWS, Azure or GCP, or local VMs — and we walk them through it. A local Kubernetes such as kind and a Git repository are enough for most of the labs. We deliberately do not hand out temporary sandboxes, because the environment they build is the one they keep.
What size are batches?
Private corporate batches run 8 to 30 engineers. Public Live & Interactive cohorts are capped at 10 so everyone gets time with the trainer.
Do attendees get a certificate?
Yes — every attendee receives a completion certificate, verifiable at devopsschool.com/certificates. Corporate batches also receive an attendance and assessment report.
What is your refund position?
If we cancel or postpone a cohort, you receive a full refund within 15 days. There is no general money-back guarantee, and GST and gateway fees are not refunded.
Is a whole course on a data format really justified?
The course is about configuration correctness, not syntax. Syntax takes an afternoon; the incidents come from implicit typing, indentation that reparents a value, anchors that behave differently across parsers, templates that emit valid but wrong documents, and the absence of any validation before deploy. That is several days of genuine material.
How long does a private YAML batch take?
Typically two days. The data model, typing, structure and anchors fit in one; schemas, templating failures, secrets and building the CI gate take the second. Teams that want the gate implemented on their own repositories usually add a third.
Which tools do you validate with?
yamllint for style and structure, JSON Schema with a language server for editor-time feedback, kubeconform for Kubernetes manifests, conftest and Open Policy Agent for policy, plus rendered-output snapshot tests for templated charts. For a private batch we standardise on whatever already exists in your pipeline.
Do you cover Helm and Kustomize?
From the YAML side. We cover why text-templating an indentation-sensitive format fails, how indent, nindent, quote and toYaml exist to patch that, how to test rendered output rather than templates, and where Kustomize overlays or a typed tool such as CUE removes the problem instead of managing it.
Should our team be using anchors and merge keys?
It depends on where the file is consumed. They work well within a single hand-written pipeline definition and badly across templated, multi-document or multi-parser workflows, where support diverges. The course gives you the failure cases so you can set a deliberate team policy rather than discovering the limits during an incident.

Still deciding?

Tell us the team, the stack and the timeline. You'll get a straight answer, not a sales sequence.

Talk to an advisor
# ready when you are

Book a YAML trainer — or ask a question first.

  • No spam, no drip sequence
  • Syllabus in 60 seconds
  • A human reply within one business day

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