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Skillsjenkins-agent-l3-deploy

jenkins-agent-l3-deploy

Deployment & operations

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Updated 10-15 22:32

About this skill

Jenkins-agent L3 deploy (no SSH)

Deploy a docker-compose stack where a Jenkins inbound agent on the target host runs deploy.py + docker compose locally. The controller never SSHes in. Runtime secrets are written to tmpfs /run/payroll-sec (file 0444, dir 0700), mounted as Docker secrets at /run/secrets/<name>, and a tiny entrypoint shim exports them to env at container start — so they are absent from docker inspect and from .env.

WHAT

Purpose và context

  • Purpose: dựng/chạy pipeline Jenkins deploy một stack docker-compose QUA inbound agent trên chính target (controller không SSH vào), với secret L3: chỉ nằm trên tmpfs, mount làm Docker secret, không có trong docker inspect lẫn .env.
  • Trigger (when to use vs the SSH variant):
    • Agent (this skill, preferred): an inbound agent runs on the target → sh steps execute locally; only a Secret file credential (the cred bundle) is needed. Controller opens no SSH outbound.
    • SSH variant: controller ssh/scp/rsync into the target (needs an SSH Username with private key credential). Use only when you cannot run an agent on the target.
    • User nói "deploy via jenkins agent", "no-ssh deploy", "agent thay vì ssh", "docker secrets L3", "ẩn secret khỏi docker inspect", "secret không nằm trên đĩa", hoặc đang nối pipeline Jenkins deploy docker-compose lên host Linux.
  • Non-goals: không dựng biến thể SSH (chỉ khi không chạy được agent); không sửa code ứng dụng để đọc secret (shim entrypoint lo); không cài Jenkins controller.

Mental model

Architecture (L3):

secret source (cred bundle)
   → deploy provisioner writes 7 files to tmpfs /run/payroll-sec  (file 0444, dir 0700 root)
   → docker-compose `secrets:` mounts each at /run/secrets/<name> (tmpfs, ro)
   → secrets-entrypoint.sh in each image: for f in /run/secrets/*; export $(UPPER basename)=$(cat f); exec "$@"
   ⇒ secret NOT in `docker inspect` (set at runtime), NOT on disk (RAM only)

postgres uses the official POSTGRES_PASSWORD_FILE; app containers use the entrypoint shim so no application code changes (avoids the Edge-runtime fs trap if a framework imports the secret module in middleware).

Input và output contract

Field Required? Ý nghĩa
In Jenkins controller reachable :8080 + :50000 từ target có agent phải kết nối được
In target Linux: Java 21, user thuộc docker group + sudo NOPASSWD có xem Gotchas 1, 4
In Secret file credential (cred bundle) có không cần SSH credential
In repo app có docker-compose.yml, deploy.py(.example), Dockerfile + secrets-entrypoint.sh có qua SCM checkout hoặc workspace có sẵn
In tick chọn service (WEB/ETL/DB/NGINX/ALL) không selective deploy; mặc định full
Out stack chạy trên target có build console Running on <target>
Out tín hiệu verify có CLEAN <c> + MOUNT <c> mọi container, smoke 200, cred bundle đã shred

Rules và capabilities

  • RULE-01 (MUST): Don't pass secrets via compose environment: (visible in docker inspect, written to .env).
  • RULE-02 (MUST): Don't store the secret files 0600 (non-root container can't read) — use 0444 + dir 0700.
  • RULE-03 (MUST): Don't rely on the SSH variant if you can run an agent — agent keeps SSH closed and runs locally.
  • RULE-04 (MUST): Don't point a file:// SCM URL at a path the controller can't see — use a network git URL.
  • RULE-05 (MUST): Gotchas 1–5 (mỗi cái đã làm hỏng một lần chạy thật) phải được bake vào setup/pipeline.
  • Capabilities: cấu hình node/credential/job trên Jenkins; chạy shell + docker + sudo trên target; đọc git repo (SCM). Không mở SSH outbound từ controller.

Failure boundaries

  • Không chạy được agent trên target → ngoài phạm vi, dùng biến thể SSH (blocked cho skill này).
  • Stage Verify in LEAK <c> hoặc NOMOUNT <c> → pipeline failed (exit 1), không coi là deploy xong.
  • Agent chết UnsupportedClassVersionError / permission denied docker-sudo / secret 0600 → failed, sửa theo bảng Gotchas rồi chạy lại.
  • Repo private chưa có deploy key / known_hosts → blocked ở checkout.

HOW

Main workflow

Step Type Inputs Action Outputs/exit Failure/next
W01 judgment hạ tầng target Chọn agent (ưu tiên) hay SSH variant quyết định không chạy được agent → dừng, SSH variant
W02 effect Jenkins + target Setup inbound agent (once): node, Java 21, agent.jar, user docker+sudo, Secret file credential agent online gotcha 1/4 → sửa, lặp
W03 effect repo app Bake secrets-entrypoint.sh vào mỗi image (ENTRYPOINT trước CMD); provisioner ghi secret 0444/0700 image + provisioner —
W04 effect job Pipeline template (Sync → Deploy → Verify), code từ SCM job chạy checkout lỗi → B02
W05 deterministic build Verify success (real signals) Running on <target>, CLEAN, MOUNT, smoke 200, cred shredded LEAK/NOMOUNT → failed

Chi tiết từng bước (nguồn chân lý cho W01–W05):

Setup the inbound agent (once)

  1. Jenkins → Manage Jenkins → Nodes → New Node: Permanent Agent, label = <target>, Remote root = /home/<user>/jenkins-agent, Launch = inbound (JNLP); copy the secret.
  2. On the target (agent must reach controller :8080 + :50000): 
    sudo apt-get install -y openjdk-21-jre-headless          # Java 21 — NOT 17 (see gotcha 1)
J21=$(ls /usr/lib/jvm/java-21-openjdk-*/bin/java | head -1)
mkdir -p ~/jenkins-agent && cd ~/jenkins-agent
curl -sO http://<CONTROLLER>:8080/jnlpJars/agent.jar
nohup "$J21" -jar agent.jar -url http://<CONTROLLER>:8080/ \
  -secret <AGENT_SECRET> -name <target> -workDir ~/jenkins-agent > agent.log 2>&1 &
    Run the agent as a user that is in the docker group AND has sudo NOPASSWD. For production replace nohup with a systemd unit (Restart=always).
  3. Credential: one Secret file credential (the cred bundle). No SSH credential.

Pipeline template (declarative)

pipeline {
  agent { label '<target>' }                 // runs ON the target, no ssh
  environment { APP = '/home/<user>/<app-dir>' }
  stages {
    stage('Sync') { steps { sh '''
      set -e
      cp -f docker-compose.yml deploy.py.example "$APP/"
      cp -f web/Dockerfile web/secrets-entrypoint.sh "$APP/web/"
      cp -f etl/Dockerfile etl/secrets-entrypoint.sh "$APP/etl/"
      cd "$APP" && cp -f deploy.py.example deploy.py
    ''' } }
    stage('Deploy') { steps { withCredentials([file(credentialsId:'app-cred', variable:'CRED')]) { sh '''
      set -e
      mkdir -p /dev/shm/pl && chmod 700 /dev/shm/pl
      cp "$CRED" /dev/shm/pl/cred.txt && chmod 600 /dev/shm/pl/cred.txt   # gotcha 3
      cd "$APP" && ln -sf /dev/shm/pl/cred.txt cred.txt
      sudo python3 deploy.py --no-nginx --etl-url /etl
      rm -f cred.txt; shred -uf /dev/shm/pl/cred.txt 2>/dev/null || rm -f /dev/shm/pl/cred.txt
    ''' } } }
    stage('Verify') { steps { sh '''
      set -e
      for c in <containers>; do
        docker inspect "$c" --format "{{range .Config.Env}}{{println .}}{{end}}" \
          | grep -iqE "SESSION_SECRET=|AUTH_USERS=|PASSWORD=|DATABASE_URL=" && { echo "LEAK $c"; exit 1; } || echo "CLEAN $c"
        docker exec "$c" ls /run/secrets >/dev/null 2>&1 && echo "MOUNT $c" || { echo "NOMOUNT $c"; exit 1; }
      done
    ''' } }
  }
}

Provide the workspace code via SCM checkout, or pre-populate the agent workspace.

secrets-entrypoint.sh (baked into each app image; ENTRYPOINT before CMD)

#!/bin/sh
set -e
if [ -d /run/secrets ]; then
  for f in /run/secrets/*; do [ -f "$f" ] || continue
    name=$(basename "$f" | tr '[:lower:]' '[:upper:]'); export "$name=$(cat "$f")"
  done
fi
exec "$@"

The provisioner (e.g. deploy.py) writes the secret files to a tmpfs dir mode 0444 (files) / 0700 (dir), then docker compose up -d.

Gotchas (each cost a failed real run — bake these in)

# Symptom Fix
1 Agent dies UnsupportedClassVersionError: class 65.0 … up to 61.0 Jenkins 2.5xx agent.jar needs Java 21, not 17.
2 App container crash-loops Permission denied /run/secrets/* Compose non-swarm bind-mounts the source file's perms; write secret files 0444 (dir 0700) so the non-root container user can read.
3 shred /dev/shm/.../cred: Permission denied Jenkins file credential is delivered 0400 (read-only); cp then chmod 600, and use `shred -uf …
4 docker/sudo "permission denied" inside the pipeline The agent process user must be in the docker group and have sudo NOPASSWD.
5 Reboot → containers fail to mount secret /run is tmpfs → secrets cleared on reboot; re-run the deploy (or a boot hook) to re-materialize before compose up.

Verify success (real signals)

  • Build console shows Running on <target> (proves it ran on the agent, not controller).
  • CLEAN <c> for every container (secret absent from docker inspect).
  • MOUNT <c> (secret present at /run/secrets).
  • App smoke (e.g. login) returns 200.
  • The cred bundle is shredded from /dev/shm (not left on disk).

Branches

ID Kind Guard Hành vi Skip / failure Rejoin
B01 user_optional chỉ deploy vài service (tick WEB/ETL/DB/NGINX thay ALL) Selective deploy: booleanParam → deploy.py --services "$SVC" + --no-deps; NGINX thì docker restart proxy riêng ALL → full; không tick gì → none = secrets only, no up W05
B02 conditional_required code lấy từ git (production: Pipeline script from SCM) cấu hình SCM; repo private → SSH deploy key + known_hosts trên controller VÀ agent lab không git server → agent git clone file:///…/repo.git W04
B03 recovery target reboot (/run tmpfs xoá secret) chạy lại deploy (hoặc boot hook) để tái tạo secret trước compose up — W05

Reference — Branch details

Selective deploy (deploy only some services, not full)

Expose booleanParam checkboxes (WEB/ETL/DB/NGINX/ALL) and pass the chosen compose services to the provisioner. Use --no-deps so a tick rebuilds only that service (not its dependency chain):

if [ "$ALL" = true ]; then SVC=""; else
  S=""; [ "$WEB" = true ] && S="$S web"; [ "$ETL" = true ] && S="$S etl"; [ "$DB" = true ] && S="$S postgres"
  [ -z "$(echo $S|xargs)" ] && SVC=none || SVC=$(echo $S|xargs)
fi
deploy.py --services "$SVC"        # "" = full ; "web etl" = those ; "none" = secrets only, no up
# provisioner runs: docker compose up -d --build --no-deps $SVC
[ "$NGINX" = true ] && docker restart <proxy-container>   # proxy is a separate container, not compose

Dependency graph (depends_on) — document it so operators know a fresh deploy needs the chain: web → etl → postgres (proxy/nginx independent). With --no-deps, tick web = ONLY web; for a clean first deploy tick the whole chain (or ALL). Verified: single ticks + combos all touch exactly the chosen services.

Pulling code from git

Production: configure the job as Pipeline script from SCM (git repo + scriptPath); Jenkins auto-checkout scm into the agent workspace, then the pipeline runs. The git URL must be reachable by BOTH controller (fetch Jenkinsfile) and agent (checkout workspace) — file:// only works on the side that owns it; in a lab without a git server, have the agent git clone file:///…/repo.git.

Private repo (tested with GitHub, build SUCCESS):

  • HTTPS anonymous clone fails for a private repo — needs auth.
  • Use an SSH deploy key (read-only) on the repo; put the private key in a Jenkins SSH Username with private key credential (username git); SCM URL git@github.com:owner/repo.git with that credentialsId.
  • Host key gotcha: add github.com to known_hosts on controller AND agent (ssh-keyscan github.com >> ~/.ssh/known_hosts) or set the git host-key strategy to "Accept first connection", else the SSH clone fails host-key verification.
  • The deploy key's public part on GitHub must match the private key in Jenkins (compare ssh-keygen -lf key.pub fingerprint vs what GitHub shows).

Validation và stopping

Stage Verify là cổng tất định: exit 1 khi có LEAK/NOMOUNT. Cần người xem: console Running on <target>, smoke login 200, /dev/shm không còn cred. Dừng khi đủ 5 tín hiệu ở "Verify success"; lỗi thuộc bảng Gotchas → sửa đúng dòng Fix rồi chạy lại build, không đoán ngoài bảng.

Examples

  • Positive: app payroll (web/etl/postgres) — agent label <target> Java 21, user trong docker group + sudo NOPASSWD, build tick ALL → console Running on <target>, CLEAN/MOUNT cho mọi container, login 200, cred bundle đã shred khỏi /dev/shm.
  • Boundary/failure: secret ghi 0600 → container web crash-loop Permission denied /run/secrets/* (gotcha 2) → provisioner đổi sang 0444 + dir 0700, chạy lại; tick chỉ WEB lần deploy đầu → web lên một mình vì --no-deps, thiếu etl/postgres → tick cả chuỗi web → etl → postgres (hoặc ALL).