Package: harmony-service-lib
harmony-service-libA library for Python-based Harmony services to parse incoming messages, fetch data, stage data, and call back to HarmonyInstallingUsing pipInstall the latest version of the package from PyPI using pip:$ pip install harmony-service-libOther methods:The package is installable from source via$ pip install git+https://github.com/harmony/harmony-service-lib-py.git#egg=harmony-service-libIf using a local source tree, run the following in the source root directory instead:$ pip install -e .UsageServices that want to work with Harmony can make use of this library to ease
interop and upgrades.  To work with Harmony, services must:Receive incoming messages from Harmony.  Currently the CLI is the only
supported way to receive messages, though HTTP is likely to follow.harmony.cliprovides helpers for setting up CLI parsing while being unobtrusive to non-Harmony
CLIs that may also need to exist.Extendharmony.BaseHarmonyAdapterand implement the#invoketo
adapt the incoming Harmony message to a service call and adapt the service
result to call to one of the adapter's#completed_with_*methods. The adapter
class provides helper methods for retrieving data, staging results, and cleaning
up temporary files, though these can be overridden or ignored if a service
needs different behavior, e.g. if it operates on data in situ and does not
want to download the remote file.A full example of these two requirements with use of helpers can be found inexample/example_service.py. Also seeadapting-new-servicesfor in depth
guidance on service development using this library, especially theinfo on proper error handling.EnvironmentThe following environment variables can be used to control the behavior of the
library and allow easier testing:REQUIRED:STAGING_BUCKET: When using helpers to stage service output and pre-sign URLs, this
indicates the S3 bucket where data will be stagedSTAGING_PATH: When using helpers to stage output, this indicates the path withinSTAGING_BUCKETunder which data will be stagedENV: The name of the environment.  If 'dev' or 'test', callbacks to Harmony are
not made and data is not staged unless also using localstackOAUTH_UID,OAUTH_PASSWORD: Used to acquire a shared EDL token
needed for downloading granules from EDL token-aware data
sources. Services using data in S3 do not need to set this.NOTE: If `FALLBACK_AUTHN_ENABLED` is set to True (CAUTION!)
 these credentials will be used to download data *as* the EDL
 application user. This may cause problems with metrics and can
 result in users getting data for which they've not approved a
 EULA.OAUTH_CLIENT_ID: The Earthdata application client ID.OAUTH_HOST: Set to the correct Earthdata Login URL, depending on
where the service is being deployed. This should be the same
environment where theOAUTH_*credentials are valid. Defaults
to UAT.OAUTH_REDIRECT_URI: A valid redirect URI for the EDL application.SHARED_SECRET_KEY: The 32-byte encryption key shared between Harmony and backend services.
This is used to encrypt & decrypt theaccessTokenin the Harmony operation message.
In a production environment, this should be injected into the container running the service
Docker image. When running the service within Harmony, the Harmony infrastructure will
ensure that this environment variable is set with the shared secret key, and the Harmony
service library will read and use this key. Therefore, the service developer need not
be aware of this variable or its value.OPTIONAL:APP_NAME: Defaults to first argument on commandline. Appears in log records.AWS_DEFAULT_REGION: (Default:"us-west-2") The region in which S3 calls will be madeUSE_LOCALSTACK: (Development) If 'true' will perform S3 calls against localstack rather
than AWSLOCALSTACK_HOST: (Development) IfUSE_LOCALSTACKtrueand this is set, will
establishbotoclient connections for S3 & SQS operations using this hostname.TEXT_LOGGER: (Default: True) Setting this to true will cause all
log messages to use a text string format. By default log
messages will be formatted as JSON.HEALTH_CHECK_PATH: Set this to the path where the health check file should be stored. This
file's mtime is set to the current time whenever a successful attempt is made to to read the
message queue (whether or not a message is retrieved). This file can be used by a container's
health check command. The container is considered unhealthy if the mtime of the file is old -
where 'old' is configurable in the service container. If this variable is not set the path
defaults to '/tmp/health.txt'.MAX_DOWNLOAD_RETRIES: Number of times to retry HTTP download calls that fail due to transient errors.OPTIONAL -- Use with CAUTION:FALLBACK_AUTHN_ENABLED: Default: False. Enable the fallback authentication that
uses the EDL application credentials. See CAUTION note above.EDL_USERNAME: The Earthdata Login username used for fallback authn.EDL_PASSWORD: The Earthdata Login password used for fallback authn.Development SetupPrerequisites:Python 3.8+, ideally installed via a virtual environmentA local copy of the codeInstall dependencies:$ make installRun linter against production code:$ make lintRun tests:$ make testBuild & publish the package:$ make publishReleasingGitHub release notes will automatically be generated based on pull request subjects.
Pull request subject lines should therefore concisely emphasize library
user-facing behavior and updates they should appear in the changelog.  If more
information is needed for release notes, note that in the PR content.