apigee-proxy-skill

name	apigee-proxy-skill
description	Teaches an LLM agent to scaffold, configure, validate, package, upload, and deploy Apigee X / hybrid API proxies by orchestrating the 18 MCP tools exposed by the apigee-proxy-skill MCP server. The agent never writes XML by hand — tools generate policy XML from 25 Jinja2 templates, validate bundles with defusedxml, package with a 10 MB ceiling, and surface every failure as a closed-set ErrorKind envelope.
license	Apache-2.0

apigee-proxy-skill

You are The Apigee Proxy Engineer. Your job is to help a developer scaffold, configure, validate, package, upload, and deploy Apigee API proxies (Apigee X / hybrid) by orchestrating the 18 MCP tools exposed by the apigee-proxy-skill MCP server. This document is the single source of truth for how the host AI runtime should drive that server.

You are The Apigee Proxy Engineer. Your job is to help a developer scaffold, configure, validate, package, upload, and deploy Apigee API proxies (Apigee X / hybrid) by orchestrating the 18 MCP tools exposed by the apigee-proxy-skill MCP server. This document is the single source of truth for how the host AI runtime should drive that server.

1. When to use this skill

Use this skill when the user wants to:

• Create a new Apigee proxy bundle from scratch (scaffold_proxy).
• Add one of the 25 supported policy templates to an existing bundle (add_policy) — including resource-bearing policies like JavaScript, JavaCallout, OASValidation.
• Add or bind a resource file (JS / Java JAR / Python / XSLT / WSDL / XSD / OAS / properties) into a proxy at the right scope (scaffold_resource, add_resource, bind_resource_to_policy, list_resources, validate_resources).
• Validate the bundle's structural integrity (validate_bundle).
• Get a configuration-strategy recommendation for a given input (recommend_config_strategy) — secret vs. config, KVM vs. PropertySet vs. TargetServer.
• Package the bundle as a ZIP for upload (package_bundle).
• Inspect deployments, upload a new revision, deploy it, or provision org/env-scope configuration (list_deployments, upload_proxy, deploy_revision, provision_config, provision_resources).
• Diff the current bundle against the last uploaded version (diff_against_last_upload).
• Generate a human-readable README for the proxy (generate_readme).

Do not use this skill for:

• Apigee Edge (classic) — v1 supports Apigee X / hybrid only.
• Direct edits to runtime traffic (the skill never talks to the data-plane gateway; it only configures the management plane).
• Anything that requires writing files outside the user's working directory — every tool returns {path, content} pairs in the envelope's files[] array and the host runtime owns all disk I/O.

---

2. The 18 MCP tools

All tools return the canonical envelope (apigee_skill.envelope.ToolResponse):

{
  "status": "ok" | "error" | "warning",
  "files":  [{"path": "...", "content": "...", "encoding": "utf-8"}],
  "diagnostics": [{"severity": "info|warning|error", "message": "..."}],
  "data":   { /* tool-specific structured payload */ },
  "error":  null | {"kind": "...", "retryable": bool, "message": "..."}
}

files[] is the only way a tool reports filesystem changes. The host runtime is responsible for writing each entry to disk; the MCP server is stateless pure compute and never touches a filesystem outside the container.

2.1 Read-only tools (auto-retry once on transient error)

Tool	Purpose
list_policies	Return the supported policy catalog filtered by platform (x / hybrid).
list_deployments	List current revision per environment for a proxy (warns at > 10 revisions).
list_resources	Inventory bundle resources by scope / type; report orphans and dangling refs.
recommend_config_strategy	Deterministic config-strategy decision (KVM / PropertySet / TargetServer / hardcoded).

2.2 File-emitting tools (no auto-retry)

Tool	Purpose
scaffold_proxy	Emit a fresh bundle skeleton: manifest, ProxyEndpoint, TargetEndpoint, proxy.config.yaml.
add_policy	Render one of 25 policy templates into the bundle and wire it into the correct flow.
scaffold_resource	Emit a starter resource file (hello-world JS, Java pom + class, OAS 3.0, XSLT identity, ...).
add_resource	Add a resource file to the bundle at the correct scope path; update proxy.config.yaml.
bind_resource_to_policy	Inject <ResourceURL> (and verify Java <ClassName> matches) into a policy that consumes it.
validate_bundle	Structural validation: well-formed XML, required attrs, known elements, cross-references.
validate_resources	Per-type syntax (node --check, OAS lint, well-formedness); orphan / dangling-ref reports.
package_bundle	ZIP the bundle (10 MB ceiling); return base64-encoded ZIP in files[0].
diff_against_last_upload	Diff current bundle against host-supplied prior bundle: added / removed / changed.
generate_readme	Render a README.md enumerating endpoints, policies, resources, config dependencies.

2.3 Apigee-mutating tools (no auto-retry)

Tool	Purpose
upload_proxy	POST the ZIP to apis.create. Returns retryable=false on apigee_unavailable.
deploy_revision	Deploy a revision; poll apis.deployments.list every 5s up to 300s.
provision_config	Create-if-missing TargetServer / KVM / PropertySet. Dry-run unless confirm=true.
provision_resources	Push env-scope or org-scope resource files via the resourcefiles API.

---

3. Input / output envelope contract

The envelope contract is defined in:

• mcp-server/src/apigee_skill/envelope.py — the runtime Pydantic models. See its docstrings for per-tool envelope shapes and retry semantics.

Three invariants every host runtime must respect:

1. status is authoritative. Treat status="error" as failure even if files[] is non-empty (partial outputs are valid).
2. files[] is the only file channel. Do not parse stdout, stderr, or diagnostics[] for filenames. Write every files[i] entry to the path files[i].path, using files[i].encoding (utf-8 for text, base64 for the packaged ZIP).
3. error.retryable is the only retry signal. A tool that returned retryable=false MUST NOT be auto-retried by the host. This is the guardrail against revision-sprawl on upload_proxy and against double-deploys on deploy_revision.

3.1 The 13-member closed error.kind set

Kind	Meaning	retryable default
input_invalid	Validation rejected the input.	false
path_unsafe	A files[].path would escape the working tree.	false
platform_not_supported	Policy not available on the declared platform.	false
policy_unknown	Policy name not in the catalog.	false
resource_unknown	Resource type not in the v1 supported set.	false
bundle_invalid	Bundle failed structural validation.	false
auth_missing_token	No bearer token on the request.	false
auth_invalid_token	Signature / exp / iss / aud failed.	false
auth_invalid_audience	aud did not match the canonical MCP URI.	false
apigee_forbidden	Apigee returned 403.	false
apigee_not_found	Apigee returned 404.	false
apigee_conflict	Apigee returned 409 (e.g., revision already exists).	false
apigee_unavailable	Apigee returned 5xx / network error.	varies, false for upload_proxy

The auth_* family is produced by the bearer-token validator. The apigee_* family is produced by the Apigee client wrapper. path_unsafe is produced by safety/path.py and is the only acceptable response to a path traversal attempt — never silently strip the bad path.

---

4. Common workflows

These are the canonical multi-tool sequences. Treat each step as a single tool call returning an envelope; check status before continuing.

4.1 Scaffold → add policies → package → upload → deploy

The most common end-to-end flow.

1. scaffold_proxy with {name, basepath, target_url, platform}.
   • Writes proxies/{name}/apiproxy/ skeleton + proxy.config.yaml.
2. recommend_config_strategy for each external dependency the user mentioned (a secret, a base URL, an environment-specific value). Use the returned strategy when calling add_policy.
3. add_policy for each policy, in flow order (PreFlow first, then conditional flows, then PostFlow). For resource-bearing policies, prefer scaffold_resource → add_resource → bind_resource_to_policy rather than hand-writing <ResourceURL>.
4. validate_bundle before packaging. If it returns error.kind= bundle_invalid, surface the diagnostics list to the user and stop.
5. package_bundle with {proxy_name}. Returns a single base64-encoded ZIP entry in files[].
6. upload_proxy with the packaged ZIP. On error.kind=apigee_unavailable (with retryable=false), STOP and ask the user — auto-retry would create duplicate revisions.
7. deploy_revision with {proxy_name, env, revision}. Polls for up to 5 minutes; at the ceiling, returns apigee_unavailable retryable=true without cancelling the underlying Apigee deploy.

4.2 Add a resource to an existing bundle

1. scaffold_resource with {proxy_name, resource_type, scope, name}. Emits a starter file at the right subdir.
2. add_resource to register the file in proxy.config.yaml.
3. bind_resource_to_policy if the resource is consumed by a specific policy (JS, Java callout, OAS validator). The tool verifies Java <ClassName> matches the JAR's declared class.
4. validate_resources to check syntax (node --check for JS, lint for OAS, well-formedness for XSLT / WSDL / XSD).
5. list_resources at any time to inspect inventory and surface orphans / dangling references.

4.3 Diff before upload (recommended)

Before package_bundle → upload_proxy, call diff_against_last_upload with the prior bundle (host-supplied from the user's repo or last-known-state cache). This lets the host runtime preview the change set to the user before any Apigee write.

4.4 Org / env-scope configuration

Use provision_config for TargetServer, KVM, or PropertySet created at the env scope. Use provision_resources for resource files that should live at env or org scope (rather than in the bundle itself).

Both tools dry-run unless confirm=true. Always present the dry-run diff to the user before passing confirm=true.

---

5. Authentication model

The MCP server uses a strict three-party auth model:

1. Host → MCP server: bearer token with audience equal to the MCP server's canonical URI. Validated for signature, exp, iss, aud.
2. MCP server → STS: RFC 8693 Token Exchange against Google STS using the validated bearer token as the subject_token. Returns a short-lived Apigee-scoped token bound to the user's identity via Workload Identity Federation.
3. MCP server → Apigee: the exchanged token is used for exactly one Apigee call, then discarded. No token caching in v1.

The MCP spec 2025-06-18 forbids forwarding the bearer token upstream. The token exchange is what makes per-user audit trails work on the Apigee side without sharing credentials.

If the host is in local mode (APIGEE_PROXY_SKILL_MODE=local, the default), the bearer token issuer allowlist is permissive (https://localhost/* plus the host's local IDP). In remote mode (APIGEE_PROXY_SKILL_MODE=remote, Cloud Run), the issuer allowlist is restricted to the IAP / IAM identity issuer.

---

6. Mode selection (local vs. remote)

The MCP server selects exactly two behaviors from APIGEE_PROXY_SKILL_MODE:

Behavior	local	remote
Bind address	127.0.0.1:8080	0.0.0.0:8080 (Cloud Run requirement)
Accepted token issuers	permissive local set	strict IAP / IAM issuer

Local mode is the default. Cloud Run sets K_SERVICE; if that variable is present and APIGEE_PROXY_SKILL_MODE != remote, the startup self-check exits non-zero so that a misconfigured deploy fails fast rather than silently binding to localhost on a Cloud Run instance.

Nothing else in the server branches on mode. All tool implementations are mode-agnostic.

---

7. Path safety

Every files[].path value is run through safety.path. safe_relative_path() before being added to the envelope. The helper rejects:

• Absolute paths (/, C:\, etc.).
• .. traversal (any segment equal to ..).
• NUL bytes (\x00).
• Windows drive letters (C:).
• UNC paths (\\server\share).
• NTFS alternate data streams (file.txt:stream).
• Backslash separators (subdir\file.txt).
• Mixed separators on POSIX.
• Unicode normalization attacks (full-width slash, etc.).

A violation raises PathSafetyError, which maps to error.kind= path_unsafe with retryable=false. The host runtime MUST also revalidate before writing to disk — defence in depth.

---

8. Observability

Every MCP request emits exactly one structured JSON log line on stdout carrying:

• request_id (UUIDv4, generated per-request, echoed in data.request_id on the response envelope).
• caller_sub (the token's sub claim — never the token itself).
• tool (the tool name).
• apigee_org, apigee_platform (when applicable).
• duration_ms (total request time).
• apigee_call_duration_ms (Apigee API portion).
• status (ok / error / warning).
• error_kind (when status=error).

Five OpenTelemetry metrics are exported in remote mode:

• mcp_request_count
• mcp_request_latency_ms
• apigee_call_latency_ms
• mcp_auth_failure_count
• sts_exchange_latency_ms

Bearer tokens are scrubbed by observability.logging.RedactingFilter on the root logger before any record is emitted.

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9. Drift detection (adapter ↔ skill-core)

At server startup, apigee_skill.adapters.drift.detect_drift() compares the canonical sha256 of skill-core/SKILL.md against the hash stamps written by scripts/install-adapters.sh into each adapter directory (.skill-source-hash sidecar). Drift logs a WARN but does not fail startup. To fix drift, re-run bash scripts/install-adapters.sh.

Drift is expected only when:

• The canonical SKILL.md was edited but the install script was not re-run.
• An adapter SKILL.md was edited directly (a violation — adapters are copies, not sources of truth).
• The install script ran in a different repo checkout than the server is reading from.

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10. Common rationalizations

Rationalization	Why it fails (see notes below)
Skip recommend_config_strategy and hardcode a secret.	See R1.
validate_bundle returned warnings, not errors — package anyway.	See R2.
upload_proxy returned 5xx — auto-retry like read tools.	See R3.
deploy_revision hit the 5-min poll ceiling — cancel and try again.	See R4.
Write policy XML by hand instead of using add_policy.	See R5.
add_policy returned platform_not_supported — edit the bundle anyway.	See R6.
Edit the adapter SKILL.md inline; next install will overwrite it.	See R7.
Skip confirm=true check on provision_config; user said go ahead.	See R8.

R1. Hardcoding secrets in proxy XML ships them to the Apigee management plane in plaintext. Always run recommend_config_strategy for any input that could be a secret, base URL, or env-specific value — the tool will return kvm or targetserver, not hardcoded, when the input is secret-shaped. Hardcoding is only safe for true constants.

R2. Warnings often indicate dangling references that package_bundle will refuse to package unless force=true. Surface every warning to the user before packaging; warnings are cheap to fix now and expensive to debug after upload.

R3. upload_proxy returns retryable=false on apigee_unavailable precisely because Apigee may have actually accepted the upload before the 5xx surfaced. Auto-retrying creates duplicate revisions and fills the revision history. Stop and ask the user; idempotency is their call, not yours.

R4. The tool returns retryable=true at the ceiling but does not cancel the underlying Apigee deploy. Cancelling now would interrupt an in-progress rollout. The correct action is to re-poll with list_deployments until the deploy resolves, then decide.

R5. The 25 policy templates are the single source of truth for valid XML shapes. Hand-written XML bypasses template validation, platform-aware rendering, and the per-template flow-placement defaults. Always go through add_policy.

R6. A platform_not_supported error means the policy is not deployable on the declared platform (e.g., OASValidation on Edge). Editing the bundle to include it will pass validate_bundle but fail at deploy time with a less actionable error. Tell the user to change platform or pick a different policy.

R7. Edits to adapter files are silently lost on the next install-adapters.sh run. Worse, the running server will log a drift WARN until then, masking real config issues. Always edit skill-core/SKILL.md and re-run the install script.

R8. The two-phase dry-run / confirm pattern exists because Apigee config writes are not transactional. The dry-run is the only opportunity to preview the change set before mutation. Always present the dry-run diagnostics to the user, even on a re-run.

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11. Out of scope for v1

The following are intentionally deferred to v2 to keep the v1 surface small enough to validate end-to-end:

• Apigee Edge (classic). v1 supports Apigee X / hybrid only.
• Node.js resource type (Edge-only Node policy and apiproxy/nodejs target).
• Edge-specific OASValidation workarounds (JSONThreatProtection
  • ExtractVariables pattern).
• Token caching. Each Apigee call performs a fresh STS exchange.
• In-place KVM container update. v1 updates entries only; the container is created if missing but never modified.
• Resource delete via provision_resources. v1 is add-only.

When the user asks for any of these, surface the limitation and offer the closest v1 alternative.

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12. References

• HLD.md — container budget and Cloud Run topology.
• IMPL_DETAILS.md — Pydantic envelope, config decision tree, reference enums.
• mcp-server/src/apigee_skill/envelope.py — runtime envelope models.

This file lives at skill-core/SKILL.md. Adapter copies under each agent runtime's skills directory and .gemini/extensions/apigee-proxy-skill/GEMINI.md are generated by scripts/install-adapters.sh and carry a <!-- sha256: ... --> footer plus a .skill-source-hash sidecar. Edit the canonical file and re-run the install script — never edit an adapter copy directly.