A remote build cache for Bazel
bazel-remote is a HTTP/1.1 and gRPC server that is intended to be used as a remote build cache for
Bazel. The cache contents are stored in a directory on disk. One can specify a maximum cache
size and bazel-remote will automatically enforce this limit and clean the cache by deleting files based on their
last access time. The cache supports HTTP basic authentication with usernames and passwords being specified by a
.htpasswd file, and also mutual TLS authentication.
Project status: bazel-remote has been serving TBs of cache artifacts per day since April 2018, both on commodity hardware and AWS servers. Outgoing bandwidth can exceed 15 Gbit/s on the right AWS instance type.
Cache entries are set and retrieved by key, and there are two types of keys that can be used:
- Content addressed storage (CAS), where the key is the lowercase SHA256 hash of the entry.
The REST API for these entries is:
/cas/<key>or with an optional but ignored instance name:/<instance>/cas/<key>. - Action cache, where the key is an arbitrary 64 character lowercase hexadecimal string.
Bazel uses the SHA256 hash of an action as the key, to store the metadata created by the action.
The REST API for these entries is:
/ac/<key>or with an optional instance name:/<instance>/ac/<key>.
Values are stored via HTTP PUT requests, and retrieved via GET requests. HEAD requests can be used to confirm whether a key exists or not.
If GET requests specify zstd in the Accept-Encoding header, then
zstandard-encoded data may be returned.
To upload zstandard compressed data, PUT requests must set
Content-Encoding: zstd and include a custom X-Digest-SizeBytes header
with the size of the uncompressed entry. The key must also refer to
the uncompressed entry.
If the --enable_ac_key_instance_mangling flag is specified and the instance
name is not empty, then action cache keys are hashed along with the instance
name to produce the action cache lookup key. Since the URL path is processed
with Go's path.Clean function before
extracting the instance name, clients should avoid using repeated slashes,
./ and ../ in the URL.
Values stored in the action cache are validated as an ActionResult protobuf message as per the
Bazel Remote Execution API v2
unless validation is disabled by configuration. The HTTP server also supports reading and writing JSON
encoded protobuf ActionResult messages to the action cache by using HTTP headers Accept: application/json
for GET requests and Content-type: application/json for PUT requests.
/status
Returns the cache status/info.
$ curl http://localhost:8080/status
{
"CurrSize": 414081715503,
"ReservedSize": 876400,
"MaxSize": 8589934592000,
"NumFiles": 621413,
"ServerTime": 1588329927,
"GitCommit": "940d540d3a7f17939c3df0038530122eabef2f19",
"NumGoroutines": 12
}
/cas/e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855
The empty CAS blob is always available, even if the cache is empty. This can be used to test that a bazel-remote instance is running and accepting requests.
$ curl --head --fail http://localhost:8080/cas/e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855
HTTP/1.1 200 OK
Content-Length: 0
Date: Fri, 01 May 2020 10:42:06 GMT
To query endpoint metrics see github.com/slok/go-http-metrics's query examples.
bazel-remote also supports the ActionCache, ContentAddressableStorage and Capabilities services in the Bazel Remote Execution API v2, and the corresponding parts of the Byte Stream API.
When using the --enable_ac_key_instance_mangling feature, clients are
advised to avoid repeated slashes, ../ and ./ strings in the instance
name, for consistency with the HTTP interface.
To query endpoint metrics see github.com/grpc-ecosystem/go-grpc-prometheus's metrics documentation.
There is (very) experimental support for a subset of the Fetch service in the
Remote Asset API
which can be enabled with the --experimental_remote_asset_api flag.
To use this with Bazel, specify --experimental_remote_downloader=grpc://replace-with-your.host:port.
This version of bazel-remote supports the Byte Stream compressed-blobs REAPI feature, which provides a way for clients to upload and download CAS blobs compressed with zstandard, in order to improve network efficiency.
Uploaded CAS blobs are stored in a zstandard compressed format by default,
which can increase the effective cache size and reduce load on the server
if clients also download blobs in zstandard compressed form. If you would
rather store CAS blobs in uncompressed form, add --storage_mode uncompressed
to your configuration.
If a YAML configuration file is specified by the --config_file command line
flag or BAZEL_REMOTE_CONFIG_FILE environment variable, then other command
line flags and environment variables are ignored. Otherwise, the flags and
environment variables listed in the help text below can be specified (flags
override the corresponding environment variables).
$ ./bazel-remote --help
bazel-remote - A remote build cache for Bazel and other REAPI clients
USAGE:
bazel-remote [options]
OPTIONS:
--config_file value Path to a YAML configuration file. If this flag is
specified then all other flags are ignored. [$BAZEL_REMOTE_CONFIG_FILE]
--dir value Directory path where to store the cache contents. This flag is
required. [$BAZEL_REMOTE_DIR]
--max_size value The maximum size of the remote cache in GiB. This flag is
required. (default: -1) [$BAZEL_REMOTE_MAX_SIZE]
--storage_mode value Which format to store CAS blobs in. Must be one of
"zstd" or "uncompressed". (default: "zstd") [$BAZEL_REMOTE_STORAGE_MODE]
--host value Address to listen on. Listens on all network interfaces by
default. [$BAZEL_REMOTE_HOST]
--port value The port the HTTP server listens on. (default: 8080)
[$BAZEL_REMOTE_PORT]
--grpc_port value The port the gRPC server listens on. Set to 0 to
disable. (default: 9092) [$BAZEL_REMOTE_GRPC_PORT]
--profile_host value A host address to listen on for profiling, if enabled
by a valid --profile_port setting. (default: "127.0.0.1")
[$BAZEL_REMOTE_PROFILE_HOST]
--profile_port value If a positive integer, serve /debug/pprof/* URLs from
http://profile_host:profile_port. (default: 0, ie profiling disabled)
[$BAZEL_REMOTE_PROFILE_PORT]
--http_read_timeout value The HTTP read timeout for a client request in
seconds (does not apply to the proxy backends or the profiling endpoint)
(default: 0s, ie disabled) [$BAZEL_REMOTE_HTTP_READ_TIMEOUT]
--http_write_timeout value The HTTP write timeout for a server response in
seconds (does not apply to the proxy backends or the profiling endpoint)
(default: 0s, ie disabled) [$BAZEL_REMOTE_HTTP_WRITE_TIMEOUT]
--htpasswd_file value Path to a .htpasswd file. This flag is optional.
Please read https://httpd.apache.org/docs/2.4/programs/htpasswd.html.
[$BAZEL_REMOTE_HTPASSWD_FILE]
--tls_ca_file value Optional. Enables mTLS (authenticating client
certificates), should be the certificate authority that signed the client
certificates. [$BAZEL_REMOTE_TLS_CA_FILE]
--tls_cert_file value Path to a pem encoded certificate file.
[$BAZEL_REMOTE_TLS_CERT_FILE]
--tls_key_file value Path to a pem encoded key file.
[$BAZEL_REMOTE_TLS_KEY_FILE]
--allow_unauthenticated_reads If authentication is enabled
(--htpasswd_file or --tls_ca_file), allow unauthenticated clients read
access. (default: false, ie if authentication is required, read-only
requests must also be authenticated) [$BAZEL_REMOTE_UNAUTHENTICATED_READS]
--idle_timeout value The maximum period of having received no request
after which the server will shut itself down. (default: 0s, ie disabled)
[$BAZEL_REMOTE_IDLE_TIMEOUT]
--max_queued_uploads value When using proxy backends, sets the maximum
number of objects in queue for upload. If the queue is full, uploads will
be skipped until the queue has space again. (default: 1000000)
[$BAZEL_REMOTE_MAX_QUEUED_UPLOADS]
--num_uploaders value When using proxy backends, sets the number of
Goroutines to process parallel uploads to backend. (default: 100)
[$BAZEL_REMOTE_NUM_UPLOADERS]
--http_proxy.url value The base URL to use for a http proxy backend.
[$BAZEL_REMOTE_HTTP_PROXY_URL]
--gcs_proxy.bucket value The bucket to use for the Google Cloud Storage
proxy backend. [$BAZEL_REMOTE_GCS_BUCKET]
--gcs_proxy.use_default_credentials Whether or not to use authentication
for the Google Cloud Storage proxy backend. (default: false)
[$BAZEL_REMOTE_GCS_USE_DEFAULT_CREDENTIALS]
--gcs_proxy.json_credentials_file value Path to a JSON file that contains
Google credentials for the Google Cloud Storage proxy backend.
[$BAZEL_REMOTE_GCS_JSON_CREDENTIALS_FILE]
--s3.endpoint value The S3/minio endpoint to use when using S3 proxy
backend. [$BAZEL_REMOTE_S3_ENDPOINT]
--s3.bucket value The S3/minio bucket to use when using S3 proxy backend.
[$BAZEL_REMOTE_S3_BUCKET]
--s3.prefix value The S3/minio object prefix to use when using S3 proxy
backend. [$BAZEL_REMOTE_S3_PREFIX]
--s3.access_key_id value The S3/minio access key to use when using S3
proxy backend. [$BAZEL_REMOTE_S3_ACCESS_KEY_ID]
--s3.secret_access_key value The S3/minio secret access key to use when
using S3 proxy backend. [$BAZEL_REMOTE_S3_SECRET_ACCESS_KEY]
--s3.disable_ssl Whether to disable TLS/SSL when using the S3 proxy
backend. (default: false, ie enable TLS/SSL)
[$BAZEL_REMOTE_S3_DISABLE_SSL]
--s3.iam_role_endpoint value Endpoint for using IAM security credentials.
By default it will look for credentials in the standard locations for the
AWS platform. [$BAZEL_REMOTE_S3_IAM_ROLE_ENDPOINT]
--s3.region value The AWS region. Required when not specifying S3/minio
access keys. [$BAZEL_REMOTE_S3_REGION]
--s3.key_version value DEPRECATED. Key version 2 now is the only supported
value. This flag will be removed. (default: 2)
[$BAZEL_REMOTE_S3_KEY_VERSION]
--disable_http_ac_validation Whether to disable ActionResult validation
for HTTP requests. (default: false, ie enable validation)
[$BAZEL_REMOTE_DISABLE_HTTP_AC_VALIDATION]
--disable_grpc_ac_deps_check Whether to disable ActionResult dependency
checks for gRPC GetActionResult requests. (default: false, ie enable
ActionCache dependency checks) [$BAZEL_REMOTE_DISABLE_GRPS_AC_DEPS_CHECK]
--enable_ac_key_instance_mangling Whether to enable mangling ActionCache
keys with non-empty instance names. (default: false, ie disable mangling)
[$BAZEL_REMOTE_ENABLE_AC_KEY_INSTANCE_MANGLING]
--enable_endpoint_metrics Whether to enable metrics for each HTTP/gRPC
endpoint. (default: false, ie disable metrics)
[$BAZEL_REMOTE_ENABLE_ENDPOINT_METRICS]
--experimental_remote_asset_api Whether to enable the experimental remote
asset API implementation. (default: false, ie disable remote asset API)
[$BAZEL_REMOTE_EXPERIMENTAL_REMOTE_ASSET_API]
--access_log_level The access logger verbosity level. If supplied, must
be one of "none" or "all". (default: all, ie enable full access logging)
[$BAZEL_REMOTE_ACCESS_LOG_LEVEL]
--help, -h show help (default: false)
# These two are the only required options:
dir: path/to/cache-dir
max_size: 100
# The form to store CAS blobs in ("zstd" or "uncompressed"):
#storage_mode: zstd
host: localhost
# The port to use for HTTP/HTTPS:
#port: 8080
# The port to use for gRPC:
#grpc_port: 9092
# If profile_port is specified, then serve /debug/pprof/* URLs here:
#profile_host: 127.0.0.1
#profile_port: 7070
# HTTP read/write timeouts. Note that these do not apply to the proxy
# backends or the profiling endpoint. Reasonable values might be twice
# the length of time that you expect a client to read/write the largest
# likely blob. Units can be one of: "s", "m", "h".
#http_read_timeout: 15s
#http_write_timeout: 20s
# Specify a certificate if you want to use HTTPS:
#tls_cert_file: path/to/tls.cert
#tls_key_file: path/to/tls.key
# If you want to use mutual TLS with client certificates:
#tls_ca_file: path/to/ca/cert.pem
# Alternatively, you can use simple authentication:
#htpasswd_file: path/to/.htpasswd
# If tls_ca_file or htpasswd_file are specified, you can choose
# whether or not to allow unauthenticated read access:
#allow_unauthenticated_reads: false
# If specified, bazel-remote should exit after being idle
# for this long. Time units can be one of: "s", "m", "h".
#idle_timeout: 45s
# If set to true, do not validate that ActionCache
# items are valid ActionResult protobuf messages.
#disable_http_ac_validation: false
# If set to true, do not check that CAS items referred
# to by ActionResult messages are in the cache.
#disable_grpc_ac_deps_check: false
# If set to true, enable metrics for each HTTP/gRPC endpoint.
#enable_endpoint_metrics: false
# Specify a custom list of histogram buckets for endpoint request duration metrics
#endpoint_metrics_duration_buckets: [.5, 1, 2.5, 5, 10, 20, 40, 80, 160, 320]
# At most one of the proxy backends can be selected:
#
# If this is 0, proxy backends won't upload blobs.
#num_uploaders: 100
# The maximum number of proxy uploads to queue, before dropping uploads.
#max_queued_uploads: 1000000
#
#gcs_proxy:
# bucket: gcs-bucket
# use_default_credentials: false
# json_credentials_file: path/to/creds.json
#
#s3_proxy:
# endpoint: minio.example.com:9000
# bucket: test-bucket
# prefix: test-prefix
# access_key_id: EXAMPLE_ACCESS_KEY
# secret_access_key: EXAMPLE_SECRET_KEY
# disable_ssl: true
#
# Provide either access_key_id/secret_access_key, or iam_role_endpoint/region.
# iam_role_endpoint can also be left empty, and figured out automatically.
# iam_role_endpoint: http://169.254.169.254
# region: us-east-1
#
#http_proxy:
# url: https://remote-cache.com:8080/cache
# If set to a valid port number, then serve /debug/pprof/* URLs here:
#profile_port: 7070
# IP address to use, if profiling is enabled:
#profile_host: 127.0.0.1
# If true, enable experimental remote asset API support:
#experimental_remote_asset_api: true
# If supplied, controls the verbosity of the access logger ("none" or "all"):
#access_log_level: noneWe publish docker images to DockerHub
that you can use with docker run. The following commands will start bazel-remote with uid
and gid 1000 on port 9090 for HTTP and 9092 for gRPC, with the default maximum cache
size of 5 GiB.
$ docker pull buchgr/bazel-remote-cache
$ docker run -u 1000:1000 -v /path/to/cache/dir:/data \
-p 9090:8080 -p 9092:9092 buchgr/bazel-remote-cacheNote that you will need to change /path/to/cache/dir to a valid directory that is readable
and writable by the specified user (or by uid/gid 65532 if no user was specified).
If you want the docker container to run in the background pass the -d flag right after docker run.
You can adjust the maximum cache size by appending --max_size=N, where N is
the maximum size in Gibibytes.
Don't name your deployment bazel-remote!
Kubernetes sets some environment variables based on this name, which conflict
with the BAZEL_REMOTE_* environment variables that bazel-remote tries to
parse.
The command below will build a docker image from source and install it into your local docker registry.
$ bazel run :bazel-remote-imageBazel remote cache server can be run on an ARM architecture (i.e.: on a Raspberry Pi).
To build for ARM, use:
$ bazel run :bazel-remote-image-arm64$ bazel build :bazel-remoteIn order to pass a .htpasswd and/or server key file(s) to the cache
inside a docker container, you first need to mount the file in the
container and pass the path to the cache. The example below also
configures TLS which is technically optional but highly recommended
in order to not send passwords in plain text.
$ docker run -v /path/to/cache/dir:/data \
-v /path/to/htpasswd:/etc/bazel-remote/htpasswd \
-v /path/to/server_cert:/etc/bazel-remote/server_cert \
-v /path/to/server_key:/etc/bazel-remote/server_key \
-p 9090:8080 -p 9092:9092 buchgr/bazel-remote-cache \
--tls_cert_file=/etc/bazel-remote/server_cert \
--tls_key_file=/etc/bazel-remote/server_key \
--htpasswd_file /etc/bazel-remote/htpasswd --max_size=5If you prefer not using .htpasswd files it is also possible to
authenticate with mTLS (also can be known as "authenticating client
certificates"). You can do this by passing in the the cert/key the
server should use, as well as the certificate authority that signed
the client certificates:
$ docker run -v /path/to/cache/dir:/data \
-v /path/to/certificate_authority:/etc/bazel-remote/ca_cert \
-v /path/to/server_cert:/etc/bazel-remote/server_cert \
-v /path/to/server_key:/etc/bazel-remote/server_key \
-p 9090:8080 -p 9092:9092 buchgr/bazel-remote-cache \
--tls_ca_file=/etc/bazel-remote/ca_cert \
--tls_cert_file=/etc/bazel-remote/server_cert \
--tls_key_file=/etc/bazel-remote/server_key \
--max_size=5To enable pprof profiling, specify a port with --profile_port.
If running inside docker, you will also need to set --profile_host to a
value other than 127.0.0.1 (--profile_host= with an empty value should
work) and add a -p mapping to the docker run commandline for the port.
See Profiling Go programs with pprof for more details.
To make bazel use remote cache, use the following flag:
--remote_cache=http://replace-with-your.host:port. You can also use the
following protocols instead of http: https, grpc or grpcs (depending on your
bazel-remote configuration).
Basic username/password authentication can be added like so:
--remote_cache=http://user:[email protected]:port
To avoid leaking your password in log files, you can place this flag in a user-specific (and .gitignore'd) bazelrc file.
To use mutual TLS with bazel, use a grpcs URL for the --remote_cache
argument, and add the following flags:
--tls_certificate=path/to/ca.cert
--tls_client_certificate=path/to/client/cert.cert
--tls_client_key=path/to/client/cert.keyFor more details, see Bazel's remote caching documentation.
To avoid per-prefix rate limiting with Amazon S3, you may want to try using
--s3.key_format=2, which stores blobs across a larger number of prefixes.
Reference:
Optimizing Amazon S3 Performance.