The `rad sync` command announces changes to the network and waits for other
nodes to be synchronized with those changes.
For instance let's create an issue and sync it with the network:
```
$ rad issue open --title "Test `rad sync`" --description "Check that the command works" -q --no-announce
```
If we check the sync status, we see that our peers are out of sync, and our
change has not yet been announced.
```
$ rad sync status --sort-by alias
╭───────────────────────────────────────────────────╮
│ Node ID Alias ? SigRefs Timestamp │
├───────────────────────────────────────────────────┤
│ (you) alice ! 1d8285b [..] │
│ z6Mkt67…v4N1tRk bob ✗ 55be805 [..] │
│ z6Mkux1…nVhib7Z eve ✗ 55be805 [..] │
╰───────────────────────────────────────────────────╯
```
Now let's run `rad sync`. This will announce the issue refs to the network and
wait for nodes to announce that they have fetched those refs.
```
$ rad sync --announce
✓ Synced with 2 seed(s)
```
Now, when we run `rad sync status` again, we can see that `bob` and
`eve` are up-to-date:
```
$ rad sync status --sort-by alias
╭───────────────────────────────────────────────────╮
│ Node ID Alias ? SigRefs Timestamp │
├───────────────────────────────────────────────────┤
│ (you) alice ✓ 1d8285b [..] │
│ z6Mkt67…v4N1tRk bob ✓ 1d8285b [..] │
│ z6Mkux1…nVhib7Z eve ✓ 1d8285b [..] │
╰───────────────────────────────────────────────────╯
```
If we try to sync again after the nodes have synced, we will already
be up to date.
```
$ rad sync --announce
✓ Nothing to announce, already in sync with 2 seed(s) (see `rad sync status`)
```
We can also use the `--fetch` option to only fetch objects:
```
$ rad sync --fetch
Fetching rad:z42hL2jL4XNk6K8oHQaSWfMgCL7ji from the network, found 2 potential seed(s).
✓ Target met: 2 seed(s)
🌱 Fetched from z6Mkux1aUQD2voWWukVb5nNUR7thrHveQG4pDQua8nVhib7Z
🌱 Fetched from z6Mkt67GdsW7715MEfRuP4pSZxJRJh6kj6Y48WRqVv4N1tRk
```
Specifying both `--fetch` and `--announce` is equivalent to specifying none:
```
$ rad sync --fetch --announce
Fetching rad:z42hL2jL4XNk6K8oHQaSWfMgCL7ji from the network, found 2 potential seed(s).
✓ Target met: 2 seed(s)
🌱 Fetched from z6Mkux1aUQD2voWWukVb5nNUR7thrHveQG4pDQua8nVhib7Z
🌱 Fetched from z6Mkt67GdsW7715MEfRuP4pSZxJRJh6kj6Y48WRqVv4N1tRk
✓ Nothing to announce, already in sync with 2 seed(s) (see `rad sync status`)
```
It's also possible to use the `--seed` flag to only sync with a specific node:
```
$ rad sync --fetch --seed z6Mkt67GdsW7715MEfRuP4pSZxJRJh6kj6Y48WRqVv4N1tRk
Fetching rad:z42hL2jL4XNk6K8oHQaSWfMgCL7ji from the network, found 3 potential seed(s).
✓ Target met: 1 preferred seed(s).
🌱 Fetched from z6Mkt67GdsW7715MEfRuP4pSZxJRJh6kj6Y48WRqVv4N1tRk
```
And the `--replicas` flag to sync with a number of nodes. First we'll
create a new issue so that we have something to announce:
```
$ rad issue open --title "Test `rad sync --replicas`" --description "Check that the replicas works" -q --no-announce
```
```
$ rad sync --replicas 1
Fetching rad:z42hL2jL4XNk6K8oHQaSWfMgCL7ji from the network, found 2 potential seed(s).
✓ Target met: 1 seed(s)
🌱 Fetched from z6Mkux1aUQD2voWWukVb5nNUR7thrHveQG4pDQua8nVhib7Z
✓ Synced with 1 seed(s)
```
Note that we see `✓ Fetched repository from 1 seed(s)` and `✓ Synced
with 1 node(s)`. This does not necessarily mean that only `bob` or
`eve` were synchronized with, since they both could have received the
announcement of the new changes. However, it does mean that we only
wait for at least 1 of the nodes to have fetched the changes from us.
It's also possible to receive an error if a repository is not found anywhere.
```
$ rad seed rad:z39mP9rQAaGmERfUMPULfPUi473tY --no-fetch
✓ Seeding policy updated for rad:z39mP9rQAaGmERfUMPULfPUi473tY with scope 'followed'
```
``` (fail)
$ rad sync rad:z39mP9rQAaGmERfUMPULfPUi473tY
✗ Error: no candidate seeds were found to fetch from
```
Or when trying to fetch from an unknown seed, using `--seed`:
```
$ rad sync --fetch rad:z39mP9rQAaGmERfUMPULfPUi473tY --seed z6MkjM3HpqNVV4ZsL5s3RAd8ThVG3VG98YsDCjHBNnGMq5o7
Fetching rad:z39mP9rQAaGmERfUMPULfPUi473tY from the network, found 1 potential seed(s).
✗ Target not met: could not fetch from [z6MkjM3HpqNVV4ZsL5s3RAd8ThVG3VG98YsDCjHBNnGMq5o7], and required 1 more seed(s)
✗ Error: Fetched from 0 preferred seed(s), could not reach 1 seed(s)
✗ Error: Could not replicate from 1 preferred seed(s)
✗ Error: z6MkjM3HpqNVV4ZsL5s3RAd8ThVG3VG98YsDCjHBNnGMq5o7: Could not connect. No addresses known.
```
Also note that you cannot sync an unseeded repo:
```
$ rad unseed rad:z39mP9rQAaGmERfUMPULfPUi473tY
[...]
```
``` (fail)
$ rad sync rad:z39mP9rQAaGmERfUMPULfPUi473tY
✗ Error: repository rad:z39mP9rQAaGmERfUMPULfPUi473tY is not seeded
```