Allow SHA-256 digests in container image references by Copilot · Pull Request #3352 · github/gh-aw-mcpg

Copilot · 2026-04-08T00:46:24Z

The container field regex rejects @sha256: digest-pinned image references, blocking immutable container image pinning for supply-chain security.

Changes

Regex pattern (validation_schema.go): Append optional (@sha256:[a-fA-F0-9]{64})? group to containerPattern
JSON schema (mcp-gateway-config.schema.json): Mirror the same pattern update
Tests: Add valid cases (image:tag@sha256:..., image@sha256:...) and invalid cases (short digest, wrong algorithm)

Now accepts:

ghcr.io/github/github-mcp-server:v0.32.0@sha256:2763823c67a0adca...
ghcr.io/github/github-mcp-server@sha256:2763823c67a0adca...

No launcher changes needed — Docker already resolves the full image:tag@sha256:... reference passed through.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

example.com
- Triggering command: /tmp/go-build2438908248/b514/launcher.test /tmp/go-build2438908248/b514/launcher.test -test.testlogfile=/tmp/go-build2438908248/b514/testlog.txt -test.paniconexit0 -test.timeout=10m0s go_.�� @v1.1.3/internal-errorsas 64/src/debug/dwa-ifaceassert x_amd64/vet --gdwarf-5 nal/version -o x_amd64/vet -plu�� /sdk@v1.43.0/tra-errorsas /sdk@v1.43.0/tra-ifaceassert x_amd64/vet -plugin-opt=-pasdocker telabs/wazero/ininfo -plugin-opt=-pas-stringintconv x_amd64/vet (dns block)
invalid-host-that-does-not-exist-12345.com
- Triggering command: /tmp/go-build2438908248/b496/config.test /tmp/go-build2438908248/b496/config.test -test.testlogfile=/tmp/go-build2438908248/b496/testlog.txt -test.paniconexit0 -test.timeout=10m0s /tmp/go-build2438908248/b393/vet.cfg g_.a --debug-prefix-map x_amd64/vet -I 0218966/b157/ -I x_amd64/vet (dns block)
nonexistent.local
- Triggering command: /tmp/go-build2438908248/b514/launcher.test /tmp/go-build2438908248/b514/launcher.test -test.testlogfile=/tmp/go-build2438908248/b514/testlog.txt -test.paniconexit0 -test.timeout=10m0s go_.�� @v1.1.3/internal-errorsas 64/src/debug/dwa-ifaceassert x_amd64/vet --gdwarf-5 nal/version -o x_amd64/vet -plu�� /sdk@v1.43.0/tra-errorsas /sdk@v1.43.0/tra-ifaceassert x_amd64/vet -plugin-opt=-pasdocker telabs/wazero/ininfo -plugin-opt=-pas-stringintconv x_amd64/vet (dns block)
slow.example.com
- Triggering command: /tmp/go-build2438908248/b514/launcher.test /tmp/go-build2438908248/b514/launcher.test -test.testlogfile=/tmp/go-build2438908248/b514/testlog.txt -test.paniconexit0 -test.timeout=10m0s go_.�� @v1.1.3/internal-errorsas 64/src/debug/dwa-ifaceassert x_amd64/vet --gdwarf-5 nal/version -o x_amd64/vet -plu�� /sdk@v1.43.0/tra-errorsas /sdk@v1.43.0/tra-ifaceassert x_amd64/vet -plugin-opt=-pasdocker telabs/wazero/ininfo -plugin-opt=-pas-stringintconv x_amd64/vet (dns block)
this-host-does-not-exist-12345.com
- Triggering command: /tmp/go-build2438908248/b523/mcp.test /tmp/go-build2438908248/b523/mcp.test -test.testlogfile=/tmp/go-build2438908248/b523/testlog.txt -test.paniconexit0 -test.timeout=10m0s -p g_.a -trimpath x_amd64/vet -I ernal/proxy -I x_amd64/vet -uns�� .cfg /tmp/go-build1090218966/b063/vet-ifaceassert x_amd64/vet -D GOAMD64_v1 -o x_amd64/vet (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

Configure Actions setup steps to set up my environment, which run before the firewall is enabled
Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

@sha256

Update containerPattern regex and JSON schema to accept optional @sha256:<64-hex-chars> suffix on container image references. This enables digest-pinned references like: - image:tag@sha256:abc123... - image@sha256:abc123... Add test cases for valid and invalid digest patterns. Agent-Logs-Url: https://github.com/github/gh-aw-mcpg/sessions/a36ac9ee-c2c2-4156-83d6-c836034383c3 Co-authored-by: lpcox <15877973+lpcox@users.noreply.github.com>

Copilot

Pull request overview

This PR updates MCP Gateway configuration validation to allow digest-pinned container image references (@sha256:<digest>), enabling immutable image pinning for improved supply-chain security.

Changes:

Extend the Go containerPattern regex to accept an optional @sha256:<64-hex> suffix.
Mirror the same container regex update in the bundled JSON Schema.
Add test cases covering valid digest-pinned references and invalid digest formats/algorithms.

Show a summary per file

File	Description
internal/config/validation_schema.go	Expands `containerPattern` to accept `@sha256:` digests during extra string-pattern validation.
internal/config/schema/mcp-gateway-config.schema.json	Updates the schema’s `container` pattern to match the new digest-accepting format.
internal/config/validation_schema_test.go	Adds validateStringPatterns coverage for digest-pinned container references.
internal/config/validation_string_patterns_test.go	Adds comprehensive valid/invalid digest-pinned container pattern test cases.

Copilot's findings

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Files reviewed: 4/4 changed files
Comments generated: 2

Copilot · 2026-04-08T01:00:56Z

internal/config/validation_schema.go

 var (
 	// Compile regex patterns from schema for additional validation
-	containerPattern = regexp.MustCompile(`^[a-zA-Z0-9][a-zA-Z0-9./_-]*(:([a-zA-Z0-9._-]+|latest))?$`)
+	containerPattern = regexp.MustCompile(`^[a-zA-Z0-9][a-zA-Z0-9./_-]*(:([a-zA-Z0-9._-]+|latest))?(@sha256:[a-fA-F0-9]{64})?$`)


Now that digest-pinned references are accepted, the container validation error hint should include an example with an @sha256:<64-hex> suffix; otherwise users who provide a digest will still see guidance that implies only :tag is supported.

Copilot · 2026-04-08T01:00:56Z

internal/config/schema/mcp-gateway-config.schema.json

@@ -76,7 +76,7 @@
          "type": "string",
          "description": "Container image for the MCP server (e.g., 'ghcr.io/example/mcp-server:latest'). This field is required for stdio servers per MCP Gateway Specification section 4.1.2.",


The schema's container field description example still only shows :latest. Since the pattern now allows digest pinning, update the description examples to include an @sha256:<digest> form so users discover the feature via the schema/docs.

Suggested change

"description": "Container image for the MCP server (e.g., 'ghcr.io/example/mcp-server:latest'). This field is required for stdio servers per MCP Gateway Specification section 4.1.2.",

"description": "Container image for the MCP server (e.g., 'ghcr.io/example/mcp-server:latest' or 'ghcr.io/example/mcp-server@sha256:<digest>'). This field is required for stdio servers per MCP Gateway Specification section 4.1.2.",

lpcox · 2026-04-08T02:12:47Z

@copilot apply changes based on the comments in this thread

…pport Agent-Logs-Url: https://github.com/github/gh-aw-mcpg/sessions/c0572733-6f1d-4e16-98d8-4d1cafd9413b Co-authored-by: lpcox <15877973+lpcox@users.noreply.github.com>

Copilot · 2026-04-08T02:15:54Z

@copilot apply changes based on the comments in this thread

Applied both review comments in 86b59ae:

Updated the validation error hint in validation_schema.go to include @sha256:<digest> example
Updated the JSON schema container field description to mention digest pinning

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

example.com
- Triggering command: /tmp/go-build2490239025/b514/launcher.test /tmp/go-build2490239025/b514/launcher.test -test.testlogfile=/tmp/go-build2490239025/b514/testlog.txt -test.paniconexit0 -test.timeout=10m0s go_.�� 5.0/deviceauth.g-errorsas 5.0/oauth2.go x_amd64/vet go nal/encoding/def-atomic /usr/local/bin/g-bool x_amd64/vet dock�� g_.a git x_amd64/vet go (dns block)
invalid-host-that-does-not-exist-12345.com
- Triggering command: /tmp/go-build673647265/b001/config.test /tmp/go-build673647265/b001/config.test -test.paniconexit0 -test.timeout=10m0s -test.count=1 /tmp/go-build673647265/b146/vet.cfg go user.email 64/pkg/tool/linu-lang=go1.25 ame (dns block)
- Triggering command: /tmp/go-build2490239025/b496/config.test /tmp/go-build2490239025/b496/config.test -test.testlogfile=/tmp/go-build2490239025/b496/testlog.txt -test.paniconexit0 -test.timeout=10m0s /tmp/go-build2490239025/b382/vet.cfg g_.a -I x_amd64/vet --gdwarf-5 --64 -o x_amd64/vet -o 1.80.0/grpclog/i-errorsas 1.80.0/grpclog/i-ifaceassert x_amd64/vet -p github.com/githu-atomic -lang=go1.25 x_amd64/vet (dns block)
nonexistent.local
- Triggering command: /tmp/go-build2490239025/b514/launcher.test /tmp/go-build2490239025/b514/launcher.test -test.testlogfile=/tmp/go-build2490239025/b514/testlog.txt -test.paniconexit0 -test.timeout=10m0s go_.�� 5.0/deviceauth.g-errorsas 5.0/oauth2.go x_amd64/vet go nal/encoding/def-atomic /usr/local/bin/g-bool x_amd64/vet dock�� g_.a git x_amd64/vet go (dns block)
slow.example.com
- Triggering command: /tmp/go-build2490239025/b514/launcher.test /tmp/go-build2490239025/b514/launcher.test -test.testlogfile=/tmp/go-build2490239025/b514/testlog.txt -test.paniconexit0 -test.timeout=10m0s go_.�� 5.0/deviceauth.g-errorsas 5.0/oauth2.go x_amd64/vet go nal/encoding/def-atomic /usr/local/bin/g-bool x_amd64/vet dock�� g_.a git x_amd64/vet go (dns block)
this-host-does-not-exist-12345.com
- Triggering command: /tmp/go-build2490239025/b523/mcp.test /tmp/go-build2490239025/b523/mcp.test -test.testlogfile=/tmp/go-build2490239025/b523/testlog.txt -test.paniconexit0 -test.timeout=10m0s /usr�� wnRn4isFk 8119778/b286/ x_amd64/vet go singleflight/sin/usr/bin/runc (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

Configure Actions setup steps to set up my environment, which run before the firewall is enabled
Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Initial plan

f189598

Copilot AI assigned Copilot and lpcox Apr 8, 2026

Copilot started work on behalf of lpcox April 8, 2026 00:46 View session

Copilot AI linked an issue Apr 8, 2026 that may be closed by this pull request

Allow SHA-256 digests in container image references #3348

Closed

Copilot AI changed the title ~~[WIP] Allow SHA-256 digests in container image references~~ Allow SHA-256 digests in container image references Apr 8, 2026

Copilot AI requested a review from lpcox April 8, 2026 00:51

Copilot finished work on behalf of lpcox April 8, 2026 00:51

lpcox marked this pull request as ready for review April 8, 2026 00:58

Copilot AI review requested due to automatic review settings April 8, 2026 00:58

Copilot started reviewing on behalf of lpcox April 8, 2026 00:58 View session

Copilot AI reviewed Apr 8, 2026

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This was referenced Apr 8, 2026

[smoke-safeoutputs] Smoke Safe-Outputs PRs: 24111974262 #3359

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[smoke-safeoutputs] Smoke Safe-Outputs Reviews: 24112108126 #3360

Closed

Copilot started work on behalf of lpcox April 8, 2026 02:13 View session

Update error hint and schema description to mention @sha256 digest su…

86b59ae

…pport Agent-Logs-Url: https://github.com/github/gh-aw-mcpg/sessions/c0572733-6f1d-4e16-98d8-4d1cafd9413b Co-authored-by: lpcox <15877973+lpcox@users.noreply.github.com>

Copilot finished work on behalf of lpcox April 8, 2026 02:16

lpcox merged commit 6333a1c into main Apr 8, 2026
13 checks passed

lpcox deleted the copilot/allow-sha256-digests branch April 8, 2026 02:40

This was referenced Apr 8, 2026

Smoke Test: Copilot - 24114798957 #3366

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Smoke Test: Copilot - 24116020478 #3368

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Smoke Test: Copilot - 24116158221 #3370

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Allow SHA-256 digests in container image references#3352

Allow SHA-256 digests in container image references#3352
lpcox merged 3 commits intomainfrom
copilot/allow-sha256-digests

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		@@ -76,7 +76,7 @@
		"type": "string",
		"description": "Container image for the MCP server (e.g., 'ghcr.io/example/mcp-server:latest'). This field is required for stdio servers per MCP Gateway Specification section 4.1.2.",

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