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https://github.com/equinix-labs/otel-cli

OpenTelemetry command-line tool for sending events from shell scripts & similar environments
https://github.com/equinix-labs/otel-cli

cli observability opentelemetry shell

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OpenTelemetry command-line tool for sending events from shell scripts & similar environments

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README 

        
# otel-cli



[![](https://img.shields.io/badge/stability-experimental-lightgrey.svg)](https://github.com/packethost/standards/blob/master/experimental-statement.md)



otel-cli is a command-line tool for sending OpenTelemetry traces. It is written in

Go and intended to be used in shell scripts and other places where the best option

available for sending spans is executing another program.



otel-cli can be added to your scripts with no configuration and it will run as normal

but in non-recording mode and will emit no traces. This follows the OpenTelemetry community's

philosophy of "first, do no harm" and makes it so you can add otel-cli to your code and

later turn it on.



Since otel-cli needs to connect to the OTLP endpoint on each run, it is highly recommended

to use a localhost opentelemetry collector that can buffer spans so that the connection

cost does not slow down your program too much.



## Getting Started



We publish a number of package formats for otel-cli, including tar.gz, zip (windows),

apk (Alpine), rpm (Red Hat variants), deb (Debian variants), and a brew tap. These

can be found on the repo's [Releases](https://github.com/equinix-labs/otel-cli/releases) page.



On most platforms the easiest way is a go get:



```shell

go install github.com/equinix-labs/otel-cli@latest

```



Docker images are published for each otel-cli release as well:



```shell

docker pull ghcr.io/equinix-labs/otel-cli:latest

docker run ghcr.io/equinix-labs/otel-cli:latest status

```



To use the brew tap e.g. on MacOS:



```shell

brew tap equinix-labs/otel-cli

brew install otel-cli

```



Alternatively, clone the repo and build it locally:



```shell

git clone [email protected]:equinix-labs/otel-cli.git

cd otel-cli

go build

```



## Examples



```shell

# run otel-cli as a local OTLP server and print traces to your console

# run this in its own terminal and try some of the commands below!

otel-cli server tui



# configure otel-cli to talk the the local server spawned above

export OTEL_EXPORTER_OTLP_ENDPOINT=localhost:4317



# run a program inside a span

otel-cli exec --service my-service --name "curl google" curl https://google.com



# otel-cli propagates context via envvars so you can chain it to create child spans

otel-cli exec --kind producer "otel-cli exec --kind consumer sleep 1"



# if a traceparent envvar is set it will be automatically picked up and

# used by span and exec. use --tp-ignore-env to ignore it even when present

export TRACEPARENT=00-0af7651916cd43dd8448eb211c80319c-b7ad6b7169203331-01



# you can pass the traceparent to a child via arguments as well

# {{traceparent}} in any of the command's arguments will be replaced with the traceparent string

otel-cli exec --name "curl api" -- \

   curl -H 'traceparent: {{traceparent}}' https://myapi.com/v1/coolstuff



# create a span with a custom start/end time using either RFC3339,

# same with the nanosecond extension, or Unix epoch, with/without nanos

otel-cli span --start 2021-03-24T07:28:05.12345Z --end 2021-03-24T07:30:08.0001Z

otel-cli span --start 1616620946 --end 1616620950.241980634

# so you can do this:

start=$(date --rfc-3339=ns) # rfc3339 with nanoseconds

some-interesting-program --with-some-options

end=$(date +%s.%N) # Unix epoch with nanoseconds

otel-cli span -n my-script -s some-interesting-program --start $start --end $end



# for advanced cases you can start a span in the background, and

# add events to it, finally closing it later in your script

sockdir=$(mktemp -d)

otel-cli span background \

   --service $0          \

   --name "$0 runtime"   \

   --sockdir $sockdir & # the & is important here, background server will block

sleep 0.1 # give the background server just a few ms to start up

otel-cli span event --name "cool thing" --attrs "foo=bar" --sockdir $sockdir

otel-cli span end --sockdir $sockdir

# or you can kill the background process and it will end the span cleanly

kill %1



# server mode can also write traces to the filesystem, e.g. for testing

dir=$(mktemp -d)

otel-cli server json --dir $dir --timeout 60 --max-spans 5

```



## Configuration



Everything is configurable via CLI arguments, json config, and environment

variables. If no endpoint is specified, otel-cli will run in non-recording

mode and not attempt to contact any servers.



All three modes of config can be mixed. Command line args are loaded first,

then config file, then environment variables.



| CLI argument         | environment variable                  | config file key          | example value  |

| -------------------- | ------------------------------------- | ------------------------ | -------------- |

| --endpoint           | OTEL_EXPORTER_OTLP_ENDPOINT           | endpoint                 | localhost:4317       |

| --traces-endpoint    | OTEL_EXPORTER_OTLP_TRACES_ENDPOINT    | traces_endpoint          | https://localhost:4318/v1/traces |

| --protocol           | OTEL_EXPORTER_OTLP_PROTOCOL           | protocol                 | http/protobuf  |

| --insecure           | OTEL_EXPORTER_OTLP_INSECURE           | insecure                 | false          |

| --timeout            | OTEL_EXPORTER_OTLP_TIMEOUT            | timeout                  | 1s             |

| --otlp-headers       | OTEL_EXPORTER_OTLP_HEADERS            | otlp_headers             | k=v,a=b        |

| --otlp-blocking      | OTEL_EXPORTER_OTLP_BLOCKING           | otlp_blocking            | false          |

| --config             | OTEL_CLI_CONFIG_FILE                  | config_file              | config.json    |

| --verbose            | OTEL_CLI_VERBOSE                      | verbose                  | false          |

| --fail               | OTEL_CLI_FAIL                         | fail                     | false          |

| --service            | OTEL_SERVICE_NAME                     | service_name             | myapp          |

| --kind               | OTEL_CLI_TRACE_KIND                   | span_kind                | server         |

| --status-code        | OTEL_CLI_STATUS_CODE                  | span_status_code         | error          |

| --status-description | OTEL_CLI_STATUS_DESCRIPTION           | span_status_description  | cancelled      |

| --attrs              | OTEL_CLI_ATTRIBUTES                   | span_attributes          | k=v,a=b        |

| --force-trace-id     | OTEL_CLI_FORCE_TRACE_ID               | force_trace_id           | 00112233445566778899aabbccddeeff |

| --force-span-id      | OTEL_CLI_FORCE_SPAN_ID                | force_span_id            | beefcafefacedead |

| --force-parent-span-id | OTEL_CLI_FORCE_PARENT_SPAN_ID       | force_parent_span_id     | eeeeeeb33fc4f3d3 |

| --tp-required        | OTEL_CLI_TRACEPARENT_REQUIRED         | traceparent_required     | false          |

| --tp-carrier         | OTEL_CLI_CARRIER_FILE                 | traceparent_carrier_file | filename.txt   |

| --tp-ignore-env      | OTEL_CLI_IGNORE_ENV                   | traceparent_ignore_env   | false          |

| --tp-print           | OTEL_CLI_PRINT_TRACEPARENT            | traceparent_print        | false          |

| --tp-export          | OTEL_CLI_EXPORT_TRACEPARENT           | traceparent_print_export | false          |

| --tls-no-verify      | OTEL_CLI_TLS_NO_VERIFY                | tls_no_verify    | false                  |

| --tls-ca-cert        | OTEL_EXPORTER_OTLP_CERTIFICATE        | tls_ca_cert      | /ca/ca.pem             |

| --tls-client-key     | OTEL_EXPORTER_OTLP_CLIENT_KEY         | tls_client_key   | /keys/client-key.pem   |

| --tls-client-cert    | OTEL_EXPORTER_OTLP_CLIENT_CERTIFICATE | tls_client_cert  | /keys/client-cert.pem  |



[Valid timeout units](https://pkg.go.dev/time#ParseDuration) are "ns", "us"/"µs", "ms", "s", "m", "h".



### Endpoint URIs



otel-cli deviates from the OTel specification for endpoint URIs. Mainly, otel-cli supports

bare host:port for grpc endpoints and continues to default to gRPC. The optional http/json

is not supported by opentelemetry-go so otel-cli does not support it. To use gRPC with an

http endpoint, set the protocol with --protocol or the envvar.



   * bare `host:port` endpoints are assumed to be gRPC and are not supported for HTTP

   * `http://` and `https://` are assumed to be HTTP unless --protocol is set to `grpc`.

   * loopback addresses without an https:// prefix are assumed to be unencrypted



### Header and Attribute formatting



Headers and attributes allow for `key=value,k=v` style formatting. Internally both

otel-cli and pflag use Go's `encoding/csv` to parse these values. Therefore, if you want

to pass commas in a value, follow CSV quoting rules and quote the whole k=v pair.

Double quotes need to be escaped so the shell doesn't interpolate them. Once that's done,

embedding commas will work fine.



```shell

otel-cli span --attrs item1=value1,\"item2=value2,value3\",item3=value4

otel-cli span --attrs 'item1=value1,"item2=value2,value3",item3=value4'

```



### Docker TLS Certificates



As of release 0.4.2, otel-cli containers are built off the latest Alpine base

image which contains the base CA certificate bundles. In order to override

these for e.g. a self-signed certificate, the best bet is to volume mount your

own /etc/ssl into the container, and it should get picked up by otel-cli and Go's

TLS libraries.



```shell

docker run -v /etc/ssl:/etc/ssl ghcr.io/equinix-labs/otel-cli:latest status

```



## Easy local dev



We want working on otel-cli to be easy, so we've provided a few different ways to get

started. In general, there are three things you need:



- A working Go environment

- A built (or installed) copy of otel-cli itself

- A system to receive/inspect the traces you generate



### 1. A working Go environment



Providing instructions on getting Go up and running on your machine is out of scope for this

README. However, the good news is that it's fairly easy to do! You can follow the normal

[Installation instructions](https://golang.org/doc/install) from the Go project itself.



### 2. A built (or installed) copy of otel-cli itself



If you're planning on making changes to otel-cli, we recommend building the project locally: `go build`



But, if you just want to quickly try out otel-cli, you can also just install it directly: `go get github.com/equinix-labs/otel-cli`. This will place the command in your `GOPATH`. If your `GOPATH` is in your `PATH` you should be all set.



### 3. A system to receive/inspect the traces you generate



otel-cli can run as a server and accept OTLP connections. It has two modes, one prints to your console

while the other writes to JSON files.



```shell

otel-cli server tui

otel-cli server json --dir $dir --timeout 60 --max-spans 5

```



Many SaaS vendors accept OTLP these days so one option is to send directly to those. This is not

recommended for production since it will slow your code down on the roundtrips. It is recommended

to use an opentelemetry-collector locally.



Another option is to use [`otel-desktop-viewer`](https://github.com/CtrlSpice/otel-desktop-viewer). 

This will bring up a server that can accept OTLP connections.



If you're not sure what to choose, try `otel-cli server tui` or `otel-desktop-viewer`.



### `otel-desktop-viewer` setup



```shell

# install the CLI tool

go install github.com/CtrlSpice/otel-desktop-viewer@latest



# run it!

$(go env GOPATH)/bin/otel-desktop-viewer



# if you have $GOPATH/bin added to your $PATH you can call it directly!

otel-desktop-viewer



# if not you can add it to your $PATH by running this or adding it to

# your startup script (usually ~/.bashrc or ~/.zshrc)

export PATH="$(go env GOPATH)/bin:$PATH"

```



The OpenTelemetry collector is listening on `localhost:4318`, and the UI will be running on

`localhost:8000`.



```shell

# start the desktop viewer (best to do this in a separate terminal)

otel-desktop-viewer



# configure otel-cli to send to our desktop viewer endpoint

export OTEL_EXPORTER_OTLP_ENDPOINT=http://localhost:4318



# use otel-cli to generate spans!

otel-cli exec --service my-service --name "curl google" curl https://google.com

```



This trace will be available at `localhost:8000`.



### SaaS tracing vendor



We've provided Honeycomb, LightStep, and Elastic configurations that you could also use,

if you're using one of those vendors today. It's still pretty easy to get started:



```shell

# optional: to send data to an an OTLP-enabled tracing vendor, pass in your

# API auth token over an environment variable and modify

# `local/otel-vendor-config.yaml` according to the comments inside

export LIGHTSTEP_TOKEN= # Lightstep API key (otlp/1 in the yaml)

export HONEYCOMB_TEAM=  # Honeycomb API key (otlp/2 in the yaml)

export ELASTIC_TOKEN= # Elastic token for the APM server.



docker run \

   --env LIGHTSTEP_TOKEN \

   --env HONEYCOMB_TEAM \

   --env ELASTIC_TOKEN \

   --name otel-collector \

   --net host \

   --volume $(pwd)/configs/otel-vendor-config.yaml:/local.yaml \

   otel/opentelemetry-collector-contrib:0.101.0 \

      --config /local.yaml

```



Then it should just work to run otel-cli:



```shell

./otel-cli span -n "testing" -s "my first test span"

# or for quick iterations:

go run . span -n "testing" -s "my first test span"

```



## Contributing



Please file issues and PRs on the GitHub project at https://github.com/equinix-labs/otel-cli



## Releases



Releases are managed by goreleaser. Currently this is limited to @tobert due to rules in

the equinix-labs organization. For now releases are not automated, but will be by the time

a v1.0 rolls out and the test suite is robust enough that we feel confident.



Testing the release: `goreleaser release --snapshot --rm-dist`



To release, a GitHub personal access token is required. The release also needs to be tagged

in git.



```shell

docker login ghcr.io # log into GitHub Docker repo

gh repo list         # make sure GitHub PAT is working

git checkout main    # release tags must be off the main branch

git pull --rebase    # get the latest HEAD

git tag v0.1.1       # tag HEAD with the next version

git push --tags      # push new tag up to GitHub

goreleaser release --rm-dist

```



## License



Apache 2.0, see LICENSE