Run one AWS CLI command across your whole fleet in parallel: hundreds of accounts in seconds, safely.
One command fanned out across every account and region at once (100
parallel workers by default, --concurrency
raises it), identities
verified before anything runs, results
merged into one stream. No more shell loops that take a coffee break to
crawl the fleet. And anything that mutates is stopped by an approval
boundary that even an AI agent with your admin credentials cannot talk
its way past. The demo above is a real terminal against the bundled
100-account sandbox fleet; replay it yourself in one command with
make build fleet-up
.
And it is measurably cheaper and faster for agents. In a 150-session, three-arm benchmark (identical Claude Opus 4.8 agents, identical prompts, same 100-account fleet), the awsmux arm was cheaper and faster than a raw-shell aws CLI arm in every cell: 1.3x to 2.9x cheaper, 2.3x to 5.4x faster, and up to 7.4x fewer output tokens, at a flat 4 turns whatever the fleet size (the CLI arm matched that only at 10 accounts, then grew to 10.5; cost and output-token differences are all Holm-adjusted p < 0.05). 138 of the 150 sessions passed environment validation, and all 12 exclusions were awsmux's own fault: an MCP startup race under concurrency, so they fell entirely in the MCP-bearing arms.
| task | fleet | cost per run (cli vs awsmux) | wall time |
|---|---|---|---|
| enumerate all VPCs | 10 accounts | $0.090 vs $0.068 (1.3x) | 34s vs 13s |
| enumerate all VPCs | 50 accounts | $0.239 vs $0.120 (2.0x) | 84s vs 23s |
| enumerate all VPCs | 100 accounts | $0.274 vs $0.193 (1.4x) | 94s vs 41s |
| find the world-open group | 50 accounts | $0.229 vs $0.079 (2.9x) | 75s vs 14s |
| find the world-open group | 100 accounts | $0.152 vs $0.098 (1.5x) | 90s vs 17s |
Full design, statistics, and caveats: docs/BENCHMARK.md.
Prerequisites: Go, Docker, and the aws CLI.
make build fleet-up && source .tmp/fleet/env.sh
That builds ./bin/awsmux
, boots a pinned LocalStack container, and
provisions a fictional 100-account fleet (10 teams, prod and stage, 5
shards, 3 regions) to break for fun. The real aws CLI talks to a real
emulated AWS on localhost, every profile is its own account (plus one
planted admin-legacy
duplicate for --dedupe
to catch), and what you change actually persists. Zero credentials, zero real AWS, zero risk.
./bin/awsmux targets --profiles 'payments-*' # verified identities, per account
./bin/awsmux run --dedupe --format jsonl -- ec2 describe-vpcs --query 'Vpcs[].VpcId'
./bin/awsmux run --profiles '*-prod-*' -- ec2 describe-security-groups \
--filters Name=ip-permission.cidr,Values=0.0.0.0/0 # find the world-open group
./bin/awsmux plan --profiles payments-prod-1 -- ec2 revoke-security-group-ingress \
--group-name legacy-bastion --protocol tcp --port 22 --cidr 0.0.0.0/0
That last one is destructive, so it will not just run: you get an immutable plan to approve first. Apply it with the token and re-run the hunt; the finding disappears for real, because the sandbox is a real (emulated) AWS. Try editing the plan file between approve and apply and watch the hash check refuse it.
make e2e
builds the binary, provisions the fleet, and smoke-tests
these same beats end to end, from STS-verified discovery through the
approval gate to a plan / approve / apply roundtrip and a tampered plan
refused by its hash (full list in
docs/ARCHITECTURE.md);
make fleet-down
removes the container.
Same commands, pointed at your own AWS setup instead of the sandbox
environment. Zero configuration of its own: awsmux discovers profiles
from your existing shared config file (~/.aws/config
) and shared
credentials file (~/.aws/credentials
), honoring AWS_CONFIG_FILE
and
AWS_SHARED_CREDENTIALS_FILE
. SSO, static keys, and
credential_process
profiles all work unchanged, because awsmux always executes through the aws CLI and verifies every identity with STS before running anything:
awsmux doctor # first run? verify aws CLI, files, profiles
awsmux targets --regions us-east-1,us-west-2
awsmux run --profiles 'prod-*' --exclude '*-sandbox' --format jsonl \
-- ec2 describe-instances --query 'Reservations[].Instances[].InstanceId'
awsmux plan -- ssm put-parameter --name /app/flag --value on --type String
awsmux approve plan-01k... # prints a one-time token, never stored
awsmux apply plan-01k... --approval-token <token>
Not seeing your profiles? awsmux doctor
shows exactly which files
were checked, how many profiles each contributed, and whether the aws
CLI and state directory are usable. awsmux targets
reports where each
profile came from (a SOURCE
column in table mode, a source
field in
jsonl: config
, credentials
, or both
).
Useful flags on run
, and on apply
/ replay
too unless noted:
--concurrency
(default 100: fleet-wide fan-out is the point; each
in-flight target is one aws CLI subprocess), --timeout 30s
,
--max-errors N
, --stop-on-access-denied
, --output-dir
(one result
file per target; not on replay
), --interactive
(checkbox target
picker; run
only). Target selection (--profiles
, --exclude
,
--regions
, --preflight
, --dedupe
) applies to run
, plan
, and
targets
; --dedupe
collapses targets that resolve to the same
account, principal, and region, and it runs the STS preflight to find
them even under --preflight=false
. Every run lands in
awsmux history
and can be re-run with awsmux replay
, which re-selects its targets from the stored execution.
Two commands, zero configuration:
go install github.com/0hardik1/awsmux@latest
claude mcp add --scope user awsmux -- awsmux mcp
There is nothing to configure. awsmux mcp
serves the agent interface
over stdio via the Model Context Protocol: no port, no daemon, no
config file, no credentials of its own. It discovers the same profiles
your terminal already has (shared config and credentials files; SSO,
static keys, and credential_process
all pass straight through) and
verifies every identity with STS before anything runs. It even locates
the aws CLI in well-known install locations when an MCP client spawns
it with a bare GUI PATH. Check the connection with /mcp
inside
Claude Code, then ask the agent "which AWS accounts can you see?"
(Drop --scope user
to register for the current project only. No Go
toolchain? git clone
make build
gives you ./bin/awsmux
.)
Claude Desktop: Settings > Developer > Edit Config, then add to
claude_desktop_config.json
(GUI apps do not read your shell PATH,
so use the absolute path from which awsmux
):
{
"mcpServers": {
"awsmux": { "command": "/absolute/path/to/awsmux", "args": ["mcp"] }
}
}
Other MCP clients (Cursor, Windsurf, Zed, ...): same shape
everywhere, a stdio server with command awsmux
and args ["mcp"]
.
The agent gets five structured tools (list_aws_targets
,
plan_aws_operation
, execute_aws_plan
, get_aws_execution
,
cancel_aws_execution
) instead of a raw shell, and it uses them on
its own: once registered there is nothing to invoke, you just ask
("find every security group open to the world in prod") and the model
reaches for the tools automatically. Read-only operations execute
freely. Anything else comes back as a plan: the agent hands you a plan
ID, you run awsmux approve <plan-id>
in your own terminal, and you paste the one-time token back into the chat for the agent to apply. The token binds to the plan's sha256 hash, so the agent cannot alter an approved plan or execute it twice.
Want to watch an agent hit the boundary with zero blast radius?
Register the sandbox fleet instead: after make build fleet-up
, point
the server at the fleet's config via environment variables (values
printed in .tmp/fleet/env.sh
):
claude mcp add awsmux-fleet \
--env AWS_CONFIG_FILE=$PWD/.tmp/fleet/aws-config \
--env AWS_SHARED_CREDENTIALS_FILE=$PWD/.tmp/fleet/aws-credentials \
--env AWSMUX_HOME=$PWD/.tmp/fleet/home \
-- $PWD/bin/awsmux mcp
The agent gets the 100-account LocalStack fleet over MCP; let it break anything it likes.
The cost and speed numbers in the table at the top come from exactly this setup. One more result from the same benchmark: when an agent was handed both a shell and the MCP tools, it picked awsmux on its own and kept nearly all of the margin.
| Class | Examples | Policy |
|---|---|---|
read_only |
||
| describe-, list-, get-*, s3 ls | ||
| runs freely | ||
mutating |
||
| create-, put-, update-*, s3 cp, s3 presign | ||
--yes , interactive confirm, or approved plan |
||
destructive |
||
| delete-, terminate-, revoke-*, s3 rm, s3 mv | ||
never --yes ; typed confirm or plan/approve/apply |
||
unknown |
||
| anything unrecognized | treated as mutating |
Where the verb convention lies, awsmux overrides it. sts calls that
mint credentials (assume-role*, assume-root, get-session-token,
get-federation-token), s3api operations that write a local outfile
(get-object, get-object-torrent, select-object-content), and s3 presign
(the URL it prints is a bearer credential for the object) are
all mutating
despite their read-style names, and s3 mv
is
destructive
because it deletes the source. Where the risk lives in an
argument rather than the name, the argument decides: s3 sync
is
mutating
, but s3 sync --delete
is destructive
.
Stable exit codes for CI and agents: 0 all succeeded, 1 some failed, 2 selection/config error, 3 approval required or rejected, 4 stopped by threshold.
A scanner pages: SSH is open to the world somewhere in the fleet. Your
agent sweeps 14 verified accounts in one read-only call, finds
sg-0a1b2c3d
in payments-prod, and proposes the revoke. The revoke is destructive, so the engine hands back a plan instead of running it. You read the plan on your phone: exact command, exact account, verified principal, hash. You approve, paste one token, and go back to sleep while the fix lands in history with the hash attached.
You can replay this exact story against a fleet of fakes right now:
make build fleet-up
.
| awsmux | awsrun | aws-vault / granted / awsume | |
|---|---|---|---|
| Fleet execution across accounts | yes | yes | no (credential tools) |
| STS identity preflight per target | yes | no | n/a |
| Risk classification + approval boundary | yes | prompt only | n/a |
| Agent interface (MCP) | yes | no | no |
100-account LocalStack test fleet (make fleet-up ) |
|||
| yes | no | no | |
| History + replay | yes | no | no |
| Runtime | single Go binary | Python + plugins | Go / varies |
The credential tools are complementary: awsmux happily executes through profiles they manage.
Architecture: the engine, the plan boundary, the executor, test-fleet internals.Benchmark: the three-arm agent-cost methodology and results behind the table above.
make setup # git hooks + pre-warm the pinned linter
make build test lint # or: go build ./... && go vet ./... && go test ./...
make fleet-up e2e # LocalStack fleet + end-to-end smoke test
make fleet-down clean
CI runs go test
and make build
on ubuntu and macos, gofmt + go vet, golangci-lint repo-wide, the LocalStack e2e smoke test on ubuntu, and a Conventional Commits check on PR titles (the commit-msg hook enforces the same convention locally).
The demo GIF at the top is a real Ghostty session against the LocalStack fleet, recorded with Kap.
Dependencies: stdlib plus cobra. Roadmap: organization-aware discovery
(--ou
plus role assumption), policy packs, Homebrew tap and release binaries.
Licensed under Apache-2.0.