YAML Considered Harmful
A presentation at DevOpsDays Amsterdam 2019 in in Amsterdam, Netherlands by Philipp Krenn
YAML Considered Harmful Philipp Krenn @xeraa
https://homepages.cwi.nl/~storm/teaching/reader/ Dijkstra68.pdf
Why YAML? Human readable Comments
Whitespace Sensitive It depends
Issues http://www.yamllint.com ports: - 80:80 - 20:20
Issues https://docs.docker.com/compose/compose-file/ #short-syntax-1 ports: - “80:80” - 73200
Issues countries: - DE - FR - GB - IE - NO - PT
Issues surname: Null windows_drive: c: version: 1.0
Abuse Behavior instead of data
Gitlab Deploying itself in 1,100+ lines https://gitlab.com/gitlab-org/gitlab-ce/blob/ master/.gitlab-ci.yml
package-and-qa: image: ruby:2.5-alpine stage: test before_script: [] dependencies: [] cache: {} variables: GIT_DEPTH: “1” API_TOKEN: “${GITLAB_BOT_MULTI_PROJECT_PIPELINE_POLLING_TOKEN}” retry: 0 script: - apk add —update openssl curl jq - gem install gitlab —no-document - source ./scripts/review_apps/review-apps.sh - wait_for_job_to_be_done “gitlab:assets:compile” - ./scripts/trigger-build omnibus when: manual only: - /.+/@gitlab-org/gitlab-ce - /.+/@gitlab-org/gitlab-ee
Helm Templates apiVersion: v1 kind: ConfigMap metadata: name: {{ .Release.Name }}-configmap labels: {{- include “mychart.app” . | nindent 4 }} data: myvalue: “Hello World” {{- range $key, $val := .Values.favorite }} {{ $key }}: {{ $val | quote }} {{- end }} {{- include “mychart.app” . | nindent 2 }}
If you want a DSL, use a DSL
Or Maybe Jsonnet
Alternative Data Format: XML <?xml version=”1.0” encoding=”UTF-8” ?> <!—Last modified 1 April 2001 by John Doe—> <title>XML Example</title> <owner> <name>John Doe</name> </owner> <database> <server>192.168.1.1</server> <ports> <port>8001</port> <port>8002</port> <port>8003</port> </ports> </database> <servers> <server name=”alpha”> <ip>10.0.0.1</ip> <dc>eqdc10</dc> </server> <server name=”beta”> <ip>10.0.0.2</ip> <dc>eqdc10</dc> </server> </servers>
Alternative Data Format: JSON { “_comment”: “Last modified 1 April 2001 by John Doe”, “title”: “JSON Example”, “owner”: { “name”: “John Doe” }, “database”: { “server”: “192.168.1.1”, “ports”: [ 8001, 8002, 8003 ] }, “servers”: { “alpha”: { “ip”: “10.0.0.1”, “dc”: “eqdc10” }, “beta”: { “ip”: “10.0.0.2”, “dc”: “eqdc10” } } }
Alternative Data Format: INI ; Last modified 1 April 2001 by John Doe [owner] name=John Doe organization=Acme Widgets Inc. [database] ; use IP address in case network name resolution is not working server=192.168.1.1 port=8001 [servers] serverAlphaIp=10.0.0.1 serverAlphaDc=eqdc10 serverBetaIp=10.0.0.2 serverBetaDc=eqdc10
Alternative Data Format: TOML # Last modified 1 April 2001 by John Doe title = “TOML Example” [owner] name = “John Doe” dob = 1970-01-01T01:00:00-02:00 # First class dates [database] server = “192.168.1.1” ports = [ 8001, 8002, 8003 ] [servers] [servers.alpha] ip = “10.0.0.1” dc = “eqdc10” [servers.beta] ip = “10.0.0.2” dc = “eqdc10”
Alternative Data Format: JSONx JSONx is an IBM® standard format to represent JSON as XML
YAML Considered Harmful Philipp Krenn @xeraa
We have all become YAML engineers, because everybody loves it, right?! Sometimes it can also burn you pretty badly and this is what this talk is about.
We dive into some common errors people encounter when working with YAML. These seem to be commonly accepted, which might be a form of the Stockholm Syndrome. And we are also taking a quick look at alternative formats and what they do (not) have to offer. Will you still love your YAML files after this talk? Let’s see…
Buzz and feedback
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