Software

Adding Subcommands to Go CLIs Command Line Interfaces (CLIs) use subcommands and flags to enable different program features. A subcommand is a grouping of related features, and flags are options for controlling those features. The openssl command provides a great example of subcommands and flags. openssl rand -base64 8 will generate 8 random bytes of data with hexadecimal output. The subcommand is “rand” and “-base64” is the flag. Other openssl subcommands like “s_client” or “x509”, provide different features and each has their own options. ...

Until recently, I haven’t had many opportunities to use Go’s generics. I ran into a case where generics make sense. Best of all, this isn’t a contrived example. I’m working on a project and using openAPI to generate API contracts. One of the generated structs contains optional fields implemented as pointers. The only required field is Name. const ( Gzip PostPailsCompression = "gzip" None PostPailsCompression = "none" ) type PostPails struct { Compression *PostPailsCompression `json:"compression,omitempty"` // MaxArchiveSize Max size (bytes) before rotating to a new archive. MaxArchiveSize *int `json:"max_archive_size,omitempty"` // Name Name of the new pail Name string `json:"name"` } I need to populate the struct with values when writing unit tests. But dealing with pointers in Go test code usually results in using temporary variables. It’s not bad, but there’s some visual noise. ...

OpenAPI is a specification for documenting HTTP APIs for both humans and machines to consume. As OpenAPI is a specification, it is language agnostic. OpenAPI relies on generators for translating the specification. There’s more than just documentation that’s generated. Generators also create language-specific interfaces, tooling, and contracts. In some ways the OpenAPI pattern reminds me of either protobuf with gRPC or ORM schema-first design. As a result, a declarative API is created by the tooling. ...

I’m looking at how object storage systems manage data on disk. Especially the idea of using append only archives with an index for fast retrieveal. While reading Facebook’s Haystack design, I noticed similarities to the tar file format and the potential to implement something similar at the local scale. Haystack Overview There are several components mentioned in the original Haystack paper, but at the core is the Haystack Store, where end user image files are physically kept. Instead of writing files directly to the filesystem, images are appended to a large file called a volume, which acts as an append-only archive. Each volume is typically capped at around 100 GB and is aligned to 8-byte offsets. Image files within this volume are referred to as needles. ...