0001: Service Config

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 .idea
+tmp

README.md

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 | GEP                             | Title          |
 |---------------------------------|----------------|
+| [0001](./proposals/0001-gep.md) | Service Config |
 
 

proposals/0001-gep.md

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+---
+MEP: 1
+Title: Service Config
+Discussion: N/A
+Implementation: N/A
+---
+
+# Service Config
+
+## Abstract
+
+Glide is going to have many configs that control both functional and non-functional aspects of the service work. 
+This GEP defines how that config is going to be set, structured and maintained across the service lifetime.
+
+## Motivation
+
+Glide is a gateway that provides a bunch of configurations to set, manage, and maintain. 
+This ensures flexibility needed to meet various needs of our end users.
+
+For example:
+
+- **Telemetry Configs**: Log Output Format, Min Log Level, OTEL Configs
+- **HTTP Server Configs**: Is enabled?, IP and Port to bind, max body size, CORS, etc.
+- **SSL/TLS Configs:** Ciphers, Cert Paths, etc.
+- **LLM Provider Configs**: API Keys, Default Parameters, Timeouts, Connection Pool Configs, etc.
+- **Routing and Load Balancing Configs**: Balancing Strategy, Routing Weights, Provider Pool Definitions, etc.
+- **Caching Configs**: Redis Connection Configs, TTLs, etc.
+- **gRPC Server Configs**: Is enabled?, IP and Port to bind, etc.
+- etc.
+
+The configuration may be versioned via git to track and audit all changes. 
+At the same time, some configs are sensitive data (notably, LLM API Keys) 
+and it must not be provided directly in the config (otherwise, they would be leaked in git).
+
+As any other config, users should be able to easily apply new changes to the config. 
+The API keys may need to be rotated from time to time.
+
+Finally, the more configs we expose, the harder may become to understand the overall config
+and find the right setting to adjust. So the config structure is an important thing here to eliminate this fatigue.
+
+### Requirements
+
+- R1: Config format must be readable
+- R2: Config format must allow comments
+- R3: Config format must be `git diff`-able and versioned
+- R4: Config must be easy to understand and reason about
+- R5: Config must allow to include sensitive values from environment variables
+- R6: Config may allow to include sensitive values from other plain files
+- R7: Config should be easy to change and operate on like "hitless" reloads 
+
+## Design
+
+There are basically a few sources of configurations possible:
+- via Glide CLI params & args
+- via environment variables
+- via a separate config file
+- via a combination of CLI, environment variables, and/or config file
+
+Setting complex nested configs via CLI or environment variables is usually a tedious error-prone process.
+So Glide will try to leverage the file as config approach as long as possible.
+
+### The Config Source
+
+Glide config is represented as a YAML file (R1, R2, R3). 
+YAML is a human-friendly version of JSON that supports comments and some useful magic like (including environment variables).
+Go has good support for the YAML format.
+
+### The Config Structure
+
+The config structure uses Glide's internal logical structure that we are going to communicate in Glide docs (R4).
+So learning more about how Glide works should give enough context to understand the config. 
+The opposite should be true as well, so knowing how the config looks will give some understanding about Glide's overall design.
+This is a route that the OTEL Collector config takes.
+
+Glide should allow you to pull values of configs from environment variables (see the config example below).
+This helps to keep sensitive information (R5) out of the config file that avoids leakages.
+
+### Config Ops
+
+Glide should be able to automatically detect changes to the config (especially, our domain-related configs like routing) and
+reload its internal representation together with the related state (R7). 
+In Kubernetes, configs are going to be represented as a configmap mounted into Glide pods. 
+On configmap change, the mounted file changes as well. So we need to watch for the file changes there. 
+Outside of Kubernetes, we may support config reloading on SIGHUP signals.
+
+### Config Example
+
+The most minimalistic possible config setup would look like this:
+
+```yaml
+routes:
+  language:
+    - name: openai-pool
+      providers:
+        - name: openai-boring
+          provider: openai
+          model: gpt-3.5-turbo
+          api_key: ${env:OPENAI_API_KEY}
+          default_params:
+            temperature: 0
+```
+
+Here is a rich config example to get better sense of the config structure:
+
+```yaml
+telemetry:
+  logging:
+    level: info
+    encoding: console # console, json
+  # other configs
+
+api:
+  http:
+    listen_addr: 0.0.0.0:7685
+    max_body_size: "2Mi"
+    tls:
+      ca_path:
+      cert_path:
+    # other configs
+
+  grpc:
+    listen_addr: 0.0.0.0:7686
+    tls:
+      ca_path:
+      cert_path:
+    # other configs
+
+routes:
+  language:
+    - name: openai-pool
+      balancing: priority # round-robin, weighted-round-robin, priority, least-latency, priority, etc.
+      providers:
+        - name: openai-boring
+          provider: openai # anthropic, azureopenai, gemini, other providers we support
+          model: gpt-3.5-turbo
+          api_key: ${env:OPENAI_API_KEY}
+          default_params:
+            temperature: 0
+        - name: anthropic-boring
+          provider: anthropic
+          model: claude-2
+          apiKey: ${env:ANTHROPIC_API_KEY}
+          default_params: # set the default request params
+            temperature: 0
+
+    - name: latency-critical-pool
+      balancing: least-latency
+      providers:
+        - name: openai-boring
+          provider: openai
+          model: gpt-3.5-turbo
+          api_key: ${env:OPENAI_API_KEY}
+          timeout_ms: 200
+        - name: anthropic-boring
+          provider: anthropic
+          api_key: ${env:ANTHROPIC_API_KEY}
+          timeout_ms: 200
+
+    - name: anthropic
+      balancing: weighted-round-robin
+      providers:
+        - name: openai
+          provider: openai
+          api_key: ${env:OPENAI_API_KEY}
+          weight: 30
+        - name: anthropic
+          provider: anthropic
+          api_key: ${env:ANTHROPIC_API_KEY}
+          weight: 70
+
+    - name: ab-test1
+      balancing: weighted-round-robin
+      providers:
+        - name: openai-gpt4
+          provider: openai
+          model: gpt-4
+          api_key: ${env:OPENAI_API_KEY}
+          weight: 50
+          default_params:
+            temperature: 0.7
+
+        - name: openai-chatgpt
+          provider: openai
+          model: gpt-3.5-turbo
+          api_key: ${env:OPENAI_API_KEY}
+          weight: 50
+          default_params:
+            temperature: 0.7
+
+        # we want to use OpenAI only in this A/B test, but that's bad resiliency wise
+        # so add Anthropic just in case OpenAI is down
+        - name: anthropic-fallback
+          provider: anthropic
+          model: claude-2
+          api_key: ${env:ANTHROPIC_API_KEY}
+          weight: 0
+
+# in case of speach-to-text models
+#  transcribers:
+#    - ...
+
+# in case of text-to-speach models
+#  synthesizers:
+#    - ...
+
+# in case of embeddings API
+#  embeddings:
+#    - ...
+
+```
+
+### References
+
+- [OTEL Collector: Config Sample](https://opentelemetry.io/docs/collector/configuration/)
+- [MLFlow AI Gateway: Configuration](https://mlflow.org/docs/latest/llms/gateway/index.html#ai-gateway-configuration)
+- [etcd: Configuration Options](https://etcd.io/docs/v3.4/op-guide/configuration/)
+- [etcd: Config Sample](https://github.com/etcd-io/etcd/blob/release-3.4/etcd.conf.yml.sample)
+- [Portkey: Config Sample](https://docs.portkey.ai/portkey-docs/portkey-features/ai-gateway/load-balancing)
+- [HashiCorp Vault: Configurations](https://developer.hashicorp.com/vault/docs/configuration)
+- [Prometheus AlertManager: Config](https://prometheus.io/docs/alerting/latest/configuration/)
+- [Kong: Config](https://github.com/Kong/kong/blob/master/kong.conf.default)
+
+## Alternatives Considered
+
+- **Using JSON as config format**. We could still use JSON as secondary config format (OTEL Collector does that), but it doesn't developer-friendly enough to be our primary config format (fails at R1, R2, and it's not too strong with R3)
+
+## Future Work
+
+- If our users want that, we could consider supporting more than one config formats like JSON or TOML.

template.md

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 ### Requirements
 
-[TBU, list all key requirements to keep in mind]
+[TBU, list all key requirements to keep in mind, use https://datatracker.ietf.org/doc/html/rfc2119 verbs]
 
 ## Design